Military Architecture deals with the design and construction of offensive, defensive, and logistical structures for warfare. It is one of the most active fields of engineering/architecture where innovations are a necessity. The amounts of money spend and the research carried out in this field surpasses that of every other field. Almost all the countries in the world set aside the maximum money for their military budget. This has been the case from the ancient Indus Valley Civilisation to the modern nuclear world. During this long period many innovations have taken place in this field. Some have come and gone, others have stayed. Military architecture can be divided into three main periods or eras. The first one being the Ancient period in which sling balls etc were constructed by humans to protect their cattle. From this nomadic stage the humans moved into a more civilized life which meant staying at one place and protecting it from enemies and animals. This led to the development of fortifications. An excellent treatise on the art of fortification, ‘Arthashastra’ was written by Kautilya during this time. It remained the sole reference to the art of fortification for a long time and this reflected the unwillingness of Indians to change with time which ultimately led to the many successful foreign invasions of this land. The Medieval period was dominated by the Mughals who brought in a culture and architecture of their own. This led to the formulation of a new system of architecture called the Indo-Saricenic Architecture. India was one of the richest countries during that time. This is clearly visible in the pomp and grandeur of the many Mughal forts constructed during that time. The forts became more massive and were also heavily decorated as opposed to those during the ancient time. This was essentially the period of fortification. As time passed by the fighting of various petty kingdoms in India further weakened the military situation in India and this paved way for the colonial rule under the British who brought in an entirely new and the most modern system of military architecture to India which included bunkers, pill boxes, trenches etc.

1.0 INTRODUCTION

Warfare has played a major role in the progress of human civilization. Our evolutionary history holds testimony to this fact. In fact technologies like ‘Electricity from Nuclear Reactors’ started as military experiments. New means of production and creation of new weapons are so much intertwined that it is much like “Which came first, the chicken or the egg?” causality dilemma. The military history of India can be traced back to several millennia. The Vedas especially the ‘Rig Veda’ describes in detail of the many wars fought by the Aryans. The two Indian epics ‘Ramayana’ and ‘Mahabharatha’ contain a wealth of knowledge about armies, warfare and techniques of warfare. India during his long history has been ruled by several dynasties. These include Mauryas, Nandas, Guptas, Rashtrakutas, Pallavas, Cholas, Pandyas, Cheras, Rajputs, Mughals and many others. For convenience sake this can be divided into three main periods

a. Pre-Ancient (7000 B.C – 500 B.C) and Ancient Period (500 B.C - 550 A.D)

b. Medieval (550 A.D – 1526 A.D) and Post-Medieval Period (1526 A.D - 1818 A.D)

c. Modern Period (1818 A.D – Present Day)

2.0 ANCIENT PERIOD (7000 B.C - 550 A.D)

The history of military architecture in India can be grouped into 3 periods

a. Pre-Indus period (before 3300 BCE)

b. Indus period (2600–1700 BCE)

c. Post-Indus period (1700–1300 BCE)

2.1 Pre-Indus Fortifications (before 3300 BCE)

It was during the Neolithic period (5000 B.C) that man began to lead an organized life. His settlements needed to be defended against wild men and men from other tribes. The presence of sling balls in cattle pens indicates that an active defense system existed during that time.

The origin of fortifications in India can be traced back to the 8th millennium B.C. There was extensive use of timber stockades around permanent settlements and cattle pens. This began to be replaced by stone footings or stone walls set in mud. These were present purely for defense of outposts and defiles. Some examples of these fortifications are:

a. Kahtras Buthi (Sind)

This fortified hill top can be dated back to the Amri Culture. The hill is steep and the top inaccessible from 3 sides. The only way up was through a gradual slope at the South end. This was the only vulnerable hill top and was first blocked by a low wall and then by four bastions guarding the entrance through a massive masonry wall.

b. Thare Hills

This is yet another hill feature and was fortified with 2 massive curved walls which were 250 ft (76.2m) apart.

c. Kot Diji

This was a village settlement near Mohenjodaro which had a citadel with strong walls and rectangular towers built of stone and mud brick. This was constructed around 3000 B.C.

However not all human settlements were fortified. It largely depended on the extent of threat to the settlement. Once a town had gained enough economic importance it was usually fortified to protect it from invasion.

2.2 Indus Valley Civilisation (2600–1700 BCE)

The Indus Valley Civilization (Mature period 2600–1700 BCE), abbreviated IVC, was an ancient civilization that flourished in the Indus River basin. Primarily centred in modern day Pakistan (Sindh and Punjab provinces) and India (Gujarat and Rajasthan), it extends westward into the Balochistan province of Pakistan. Remains have been excavated from Afghanistan, Turkmenistan and Iran, as well. The mature phase of this civilization is technically known as the Harappan Civilization, after the first of its cities to be unearthed: Harappa in Pakistan.

2.3 Origin of defence fortifications in Indus Valley Civilisation

Indus fortifications were usually massive and impressive structures with 12.1 – 15.2m thick wall including a 1.2m to 1.5m thick facing of burnt brick. The walls were given added strength by square towers at regular intervals garrisoned by defenders, the towers also served as storehouses for defensive weapons and missiles. Salients were added to cover the blind spots in defense. Elaborate gateways were designed with curved entrances, ramps and steps with a view to prevent surprise and to defeat a sudden rush by attackers. Fortifications were also employed for the protection of outposts and important defiles.

2.4 Harappa

The city of Harappa located on the banks of Ravi River covered an area of around 5 km. (Fig 1) The fortification of the city was in the form of a parallelogram 420m long North-South and 196.5m wide East-west. The outer wall had a basal width of 12m and a height of over 10.5m, constructed of mud bricks on a mud brick core over a rampart of mud and debris 3-6m in height. The rampart had a mud brick core. The wall was externally riveted with a facing of baked brick and reinforced at intervals by rectangular towers or salients which provided an elaborate system of enfilade. There were 2 gateways one each on North and West with the one on North being the main one. On the North-Western corner of the citadel there was a tower which afforded additional protection to the main entrance in the North wall. A curved re-entrant in the wall led to the western entrance which afforded close protection by a bastion. The entrance led onto ramps and terraces which were commanded by the ramparts as well as guard rooms.

The revetment of the outer wall, initially built with brick bats was later rebuilt with whole bricks. At a still later date defenses on the North-Western corner were enlarged and straightened; two smaller entrances were blocked. The crenellated outer wall which rose to 7.5m in height rested on a great rampart, 3-6m high which was essentially an anti-flood bund but also helped to raise the defenses. The increased height enlarged the field of view of the defenders and improved its defensive potential. The top of the 7.5m high wall must have been crenellated.

2.5 Mohenjodaro

There is nothing much special about the defenses of Mohenjodaro except the fact that they made use of slings and baked clay missiles to attack the enemy at some distance. (Fig 2) Platforms were built to accommodate sling shooters.

2.6 Post-Indus Period (1700–1300 BCE)

2.7 Fortification according to Arthashastra:

An entire section of Kautilya’s Arthashastra has been devoted to the construction of forts (durga).

A fort should be located in a naturally defensible point. It should be surrounded by water, marshes, thick undergrowth. There should not be any vantage point for the enemy like a small island in water, caves or small hills whose elevation can be used to advantage by the enemy.

Kautilya also tells us how a ‘Sthaniya’ or administrative capital of a state should be laid down. He recommends that 3 moats, 6 feet apart each 84, 72 and 50 feet wide respectively must be dug. There depths should be ½ to ¾ of their width or down till the water table (Fig 3). There widths at base should be 1/3 of their width at top. It should be stocked with crocodiles and lotus plants.

Ramparts have to be constructed that are 36 feet in height and 72 feet in width at base using earth excavated from moats. The remaining sand should be used to level the site for the city. The top of the rampart should be compacted flat by elephants and bullocks. Its front should be of convex shape with thorny bushes and poisonous creepers planted on it. A brick or stone parapet 18-36 feet in height should be constructed at the top. A wooded parapet would be unsuitable at it would be susceptible to fire. Turrets of square shaped should be constructed at intervals of 180 feet with a tower in between them. At intervals of 45 feet in between a turret and a tower wooden merlin of planks should be erected to accommodate 3 archers with openings for arrows. Each tower should have 2 storeys with a hall and accommodation for guards. An escape route with a trap door should lead from inside the walls to a place well away from the likely location of the besieger.

A covered track should be dug outside the ramparts with booby traps like concealed pits and other devices (Fig 4). The main gateway should be about 30-48 feet wide. The space behind the gate would be occupied by a hall, a guard room and a well for water. The 2 leaves of the main gate should cover about 3/5 of the opening. A 5 hasta (2.3m) high side door should be made next to the main gate. An elephant passage, half the width of the opening should also be provided it should be secured with 4 elephant bars. A bridge capable of easy removal as broad as the opening of the gateway should span the moat. A channel dug in the vicinity of the gate should store the immediate requirements of the defenders like stones, spades, axes, hammers, arrows, choppers ets.

3.0 MEDIEVAL PERIOD (515 A.D – 1818 A.D)

3.1 Medieval Fortification

Medieval fortification is the military aspect of medieval technology that covers the development of fortification construction and use. During this millennium, fortifications changed warfare, and in turn were modified to suit new tactics, weapons and siege techniques. During the major part of the medieval period India was ruled by the Mughal Empire. Most of the major forts present now in India were constructed by the Mughals during this period. They combined the best in Indian and Persian military architecture which created a system of military architecture that was impenetrable for nearly 300 years until the British came.

The Mughal Empire was an Islamic imperial power of the Indian subcontinent which began in the early 16th century, ruled most of the subcontinent by the late 17th and early 18th centuries, and ended in the mid-19th century. The Mughal Emperors were of Turko-Mongol, and later Rajput and Persian, descent, and developed a highly sophisticated mixed Indo-Persian culture. At the height of its power, around 1700, it controlled most of the Subcontinent - extending from present-day Bangladesh to Kashmir and part of what is now Badakshan. Its population at that time has been estimated as between 110 and 130 million, over a territory of over 4 million km² (1.5 million mi²).Following 1725 it declined rapidly. Its decline has been variously explained as caused by wars of succession, agrarian crises fueling local revolts, the growth of religious intolerance, and British colonialism.

3.2 Parts of a Medieval Fort

3.3 Towers

Towers of Medieval castles were usually made of stone or sometimes (but rarely) wood. Often toward the later part of the era they included battlements and arrow loops. Arrow loops were vertical slits in the wall where archers from the inside shot arrows through at the attackers, but they made it extremely difficult for attackers to get many arrows through back at the defenders.

3.4 City Walls

The exact nature of the walls of a medieval town or city would depend on the resources available for building them, the nature of the terrain and the perceived threat. Especially where stone was readily available for building, the wood will have been replaced by stone to a higher or lower standard of security.

In any case, the wall will have had an internal and an external pomoerium. This was a strip of clear ground immediately inside or outside the wall.

An external pomoerium, stripped of bushes and building, gave defenders a clear view of what was happening outside and an unobstructed field of shot. An internal pomoeriun gave ready access to the rear of the curtain wall to facilitate movement of the garrison to a point of need. By the end of the sixteenth century, the word had developed further in common use, into pomery.

3.5 Materials

Materials that were used in the building of castles varied through history. Wood was used extensively for a long time. They were cheap and were quick to construct. The reason wood fell into disuse as a material is that it is quite flammable. Soon stone became more popular.

Stone castles took years to construct depending on the overall size of the castle. Stone was stronger and of course much more expensive than wood. Most stone had to be quarried miles away, and then brought to the building site.

3.6 Costs

Costs for the walls depended on the material used. Wood would cost very little and was quick but was weak. Stone was strong but very expensive and time consuming.

3.7 Manpower

Manpower in the Medieval era in traditional governments in India consisted mainly of slave labor and low-class laborers. Slaves came from conquered nations or were traded from other nations. They worked eight to twelve hours everyday, except (if they were forced to convert) on religious holidays. Slaves were paid only in old or soiled food and bad shelter. Laborers were only a step above slaves, paid with at least some currency and generally decent food and shelter (though they are considered in debt to the employer for such materials and not be paid because of this).

3.8 Walls

* Height: Varied from castle to castle

* Width: usually 2.5-6 m (8-20 ft) thick

3.9 Gates

An entranceway creates problems in warfare, as it is the weakest point on any wall. Entranceways must be able to be open enough to allow supplies to be brought in, yet be able to provide a solid wall to an enemy. Ditches and moats must be passable in peace, yet able to be uncovered during a siege, and walls must be broken enough to allow easy passage, yet not compromise the security of the compound.

Multiple wall and ditch systems compound the problem, leading to the necessity of a controlled entranceway.

3.10 Killing fields

A Killing field was an area between the main wall and a secondary wall, so when the first wall was breached the attackers would run into the killing field to be confronted by another wall from which soldiers bombarded them. Soldiers would be positioned atop the second wall and armed with any variety of weapons, ranging from bows to crossbows to simple rocks.

3.11 Moats

A moat was a common addition to medieval fortifications, and the principal purpose (just as in antiquity) to make the walls harder to assail and increasing their effective height. In many instances, natural water paths were used as moats, and often extended through ditches to surround as much of the fortification as possible. Provided this was not so unnaturally contrived as to allow an attacker to drain the system, it served two defensive purposes. It made approaching the curtain wall of the castle more difficult and the undermining of the wall virtually impossible. To position a castle on a small island was very favourable from a defensive point of view, although it made deliveries of supplies and building materials more cumbersome and expensive.

3.12 Keeps

A keep is a strong central tower which normally forms the heart of a castle. Often the keep is the most defended area of a castle, and as such may form the main habitation area for a noble or lord, or contain important stores such as the armoury or the main well.

3.13 Stairs

At this time, internal stairways (Fig 5) in fortified buildings were generally constructed so as to wind up a cylindrical well, and designed to give an advantage to a defender. The principle usually adopted was that the defender was likely to be positioned higher than an assailant who was presumed to have entered on the ground floor. As most people are right-handed, and the defender higher up, the stair was constructed as a left-handed helix, forcing the assailant to fight with his sword hand close to the central pillar, the newel of the stair, thereby limiting his capacity for sword play, while the defender could more comfortably reach around with his sword arm nearer the outer wall of the well.

Conversely, spiral stairs in churches are usually, but not invariably, in the form of a right-hand helix.

Stairs were also constructed to contain trick or stumble steps. These were steps that had different rise height or thread depth from the rest and would cause anyone running up the stairs to stumble or fall, so slowing down the attackers’ progress.

Now let us take a look at some of the Medieval Forts in India which incorporates these features

3.14 Agra Fort

Agra Fort is a UNESCO World Heritage site located in Agra, India. The fort is also known as Lal Qila, Fort Rouge and Red Fort of Agra. It is about 2.5 km northwest of its much more famous sister monument, the Taj Mahal. The fort can be more accurately described as a walled palatial city (Fig 6).

The fort has a semi-circular plan, its chord lying parallel to the river. Its walls are seventy feet high. Double ramparts have massive circular bastions are regular intervals as also battlements, embrasures, machicolations and string courses. Four gates were provided on its four sides, one Khizri gate opening on to the river.

Two of the gates are called the ‘Delhi Gate’ and the ‘Lahore Gate’. Lahore Gate is also popularly also known as the Amar Singh Gate, named after Amar Singh Rathore.

The Delhi Gate, which faces the city, is considered the grandest of the four gates. It leads to an inner gate called the Hathi Pol (Elephant Gate) where two life sized stone elephants with their riders stand guard. A draw-bridge, the slight ascent and 90 degree turns before each subsequent gate make it impregnable: during a siege, attackers had elephants crush the gates. Without a level, straight run-up to gather speed, which is prevented by this layout, they are not effective, though.

3.15 The Red Fort

The Delhi Fort also known as Lal Qil’ah, or Lal Qila. The Red Fort (Fig 7 and 7.1) and the city of Shahjahanabad was constructed by the Emperor Shah Jahan in 1639 A.D. The layout of the Red Fort was organised to retain and integrate this site with the Salimgarh Fort. The fortress palace is an important focal point of the medieval city of Shahjahanabad. The planning and aesthetics of the Red Fort represent the zenith of Mughal creativity which prevailed during the reign of Emperor Shahjahan. This Fort has had many developments added on after its construction by Emperor Shahjahan. The significant phases of development were under Aurangzeb and later Mughal rulers. Important physical changes were carried out in the overall settings of the site after the First War of Independence during British Rule in 1857. After Independence, the site experienced a few changes in terms of addition/alteration to the structures. During the British period the Fort was mainly used as a cantonment. The Red Fort was the palace for Mughal Emperor Shah Jahan’s new capital, Shahjahanabad, the seventh Muslim city in the Delhi site. He moved his capital from Agra in a move designed to bring prestige to his reign, and to provide ample opportunity to apply his ambitious building schemes and interests.

The fort lies along the Yamuna River, which fed the moats that surround most of the wall. The wall at its north-eastern corner is adjacent to an older fort, the Salimgarh Fort, a defense built by Islam Shah Suri in 1546. Construction on the Red Fort began in 1638 and was complete by 1648.

On 11 March 1783, Sikhs entered Red Fort in Delhi and occupied the Diwan-i-Am. The city was essentially surrendered by the Mughal wazir in cahoots with his Sikh Allies. This task was carried out under the command of the Sardar Baghel Singh Dhaliwal of the Karor Singhia misl.

The Red Fort stands at the eastern edge of Shahjahanabad, and gets its name from the massive wall of red sandstone that defines its four sides. The wall is 1.5 miles (2.5 km) long, and varies in height from 60ft (16m) on the river side to 110 ft (33 m) towards the city. Measurements have shown that the plan was generated using a square grid of 82 m.

3.16 Sivaji’s Forts

Shivaji is well known for his forts; he was in possession of around three hundred at the time of his death. Many, like Panhala,Rajgad existed before him but others like Sindhudurg and Pratapgad (Fig were built by him from scratch. These forts were central to his empire and their remains are among the foremost sources of information about his rule. The French missionary Father Fryer witnessed the fortifications of Gingee, Madras, built by Shivaji after its conquest, and appreciated his technical knowhow and knowledge.

The hill fort Salher in Nashik district was at a distance of 1200 km from the hill fort Jingi, near Chennai. Over such long distance, hill forts were supported by seaforts. Sea fort Colaba,near Mumbai was at a distance of 500 km from seafort Sindhudurg. These all forts were put under a havaldar with a strong garrison. Strict discipline was followed. These forts proved useful during Mughal-Maratha wars.

Along with Rana Kumbha of Mewar and Raja Bhoj of Shilahar, he stands as a grand figure in the art of fortification in Indian sub-continent. There are a number of legends about these forts. Even today thousands of youths visit these forts in his memory.

Notable features of Shivaji’s forts include:

1. Design changes with the topography and in harmony of the contour, no monotony of design

2. No ornate palaces or dance floors or gardens

3. No temple complexes

4. Not much difference in the area of higher or lower ranks

5. Marvelous acoustics in the capital

6. Sanskritization of fort names

7. Community participation in the defense of forts

8. Three tier administration of forts

9. System of inspection of forts by higher ups including the king

10. Distinct feature of forts like double line fortification of Pratapgad, citadel of Rajgad

11. Foresight in selection of sites

4.0 MODERN PERIOD (1818 A.D – Present Day)

It was the British which brought the most modern system of military architecture to India. Over 100 years of the colonial rule led to the modernization of the Indian Military and Military Architecture at least to very small scale. During this period many new systems like the trench system, bunkers etc were brought to India. Unlike in the other two periods where changes were welcomed by the Indians we were forced to change during this period.

4.1 Trenches - Origin and evolution of trench system

Early in the war the British defensive doctrine suggested a main trench system of three parallel lines with each line connected by communications trenches. The point at which a communications trench intersected the front trench was of critical importance and was usually heavily fortified. The front trench was lightly garrisoned and typically only occupied in force during “stand to” at dawn and dusk.

Between 70 and 100 yards behind the front trench was located the support (or “travel”) trench to which the garrison would retreat when the front trench was bombarded. Between 300 and 500 yards further to the rear was located the third reserve trench where the reserve troops could amass for a counter-attack, if the front trenches were captured.

This defensive layout was soon rendered obsolete as the power of the artillery grew. However, in certain sectors of the front, the support trench was maintained as a decoy to attract the enemy bombardment away from the front and reserve lines. Fires were lit in the support line to make it appear inhabited and any damage due to shellfire was immediately repaired.

Temporary trenches were also built. When a major attack was planned, assembly trenches would be dug near the front trench. These were used to provide a sheltered place for the waves of attacking troops who would follow the first waves leaving from the front trench. “Saps” were temporary, unmanned, often dead-end, utility trenches dug out into no man’s land. They fulfilled a variety of purposes such as connecting the front trench to a listening post close to the enemy wire or providing an advanced “jumping-off” line for a surprise attack.

4.2 Development of trench systems

When one side’s front line bulged towards the opposition, a “salient” was formed. The concave trench line facing the salient was called a “re-entrant”. Large salients were perilous for their occupants because they could be assailed from three sides.

Behind the front system of trenches there were usually at least two more partially prepared trench systems, kilometres to the rear, ready to be occupied in the event of a retreat. The Germans often prepared multiple redundant trench systems; in 1916 their Somme front featured two complete trench systems, one kilometre apart, with a third partially complete system a further kilometre behind.

This duplication made a decisive break-through virtually impossible. In the event that a section of the first trench system was captured, a “switch” trench would be dug to connect the second trench system to the still-held section of the first.

The Germans made something of a science out of designing and constructing defensive works. They used reinforced concrete to construct deep, shell-proof, ventilated dugouts as well as strategic strongpoints. They were more willing than their opponents to make a strategic withdrawal to a superior, prepared defensive position. They were also the first to apply the concept “defence in depth” where the front line zone was hundreds of yards deep and contained a series of redoubts rather than a continuous trench.

Each redoubt could provide supporting fire to its neighbours and while the attackers had freedom of movement between the redoubts they would be subjected to withering enfilade fire. The British eventually adopted a similar approach but it was incompletely implemented when the Germans launched the 1918 “Spring Offensive” and proved disastrously ineffective.

4.3 Trench construction

Trenches were never straight but were dug in a square-toothed pattern that broke the line into bays connected by traverses. This meant that a soldier could never see more than 10 metres or so along the trench, consequently the entire trench could not be enfiladed if the enemy gained access at one point or if a bomb or shell landed in the trench, the shrapnel could not travel far.

The side of the trench facing the enemy was called the parapet and had a fire step. The rear of the trench was called the parados. The parados protected the soldier’s back from shrapnel from shells falling behind the trench. If the enemy captured the trench then the parados would become their “parapet”. The sides of the trench were revetted with sandbags, wooden frames and wire mesh. The floor of the trench was usually covered by wooden duckboards.

Dugouts of varying degrees of luxury would be built in the rear of the support trench. British dugouts were usually 8 to 16 feet deep, whereas German dugouts were typically much deeper; usually a minimum of 12 feet deep and sometimes dug 3 stories down with concrete staircases to reach the upper levels.

To allow a soldier to see out of the trench without exposing his head, a loophole would be built into the parapet (Fig 12). A loophole might simply be a gap in the sandbags or it might be fitted with a steel plate. German snipers used armor-piercing bullets that allowed them to penetrate loopholes.

The other means to see over the parapet was the trench periscope - in its simplest form, just a stick with two angled pieces of mirror at the top and bottom.

4.4 Digging trenches

There were three standard ways to dig a trench: entrenching, sapping and tunnelling.

a. Entrenching, where a man would stand on the surface and dig downwards, was most efficient as it allowed a digging party to dig the length of the trench simultaneously. However, entrenching left the diggers exposed above ground and hence could only be carried out when free of observation such as in a rear area or at night.

b. Sapping involved extending the trench by digging away at the end face. The diggers were not exposed but only one or two men could work on the trench at a time.

c. Tunneling was like sapping except that a “roof” of soil was left in place while the trench line was established then removed when the trench was ready to be occupied. The guidelines for British trench construction stated that it would take 450 men 6 hours (at night) to complete 250 metres of a front line trench system. Thereafter the trench would require constant maintenance to prevent deterioration caused by weather or shelling.

4.5 Bunker

A military bunker (Fig 13) is a hardened shelter, often buried partly or fully underground, designed to protect the inhabitants from falling bombs or other attacks. They were used extensively in World War I, World War II, and the Cold War for weapons facilities, command and control centers, and stores (for example, in the event of nuclear war).

4.6 Types

a. Trench

This type of bunker is a small concrete structure, partly dug into the ground, which is usually a part of a trench system. Such bunkers give the defending soldiers better protection than the open trench and also include top protection against aerial attack (grenades, mortar shells t). They also provide shelter against he weather.

The front bunker of a trench system usually includes machine guns or mortars and forms a dominant shooting post. The rear bunkers are usually used as command posts or Tactical Operations Center (TOC), for storage and as field hospitals to attend to wounded soldiers.

b. Pillbox

Dug-in guard posts (with loopholes through which to fire weapons) and made from concrete are also known as “pillboxes”. The originally jocular name arose from their perceived similarity to the cylindrical boxes in which medical pills were once sold. They are in effect a trench firing step hardened to protect against small-arms fire and grenades and raised to improve the field of fire.

The concrete nature of pillboxes means that they are a feature of prepared positions. This is likely to have been the time when they acquired their incongruous English name. The Oxford English Dictionary’s earliest record of the use of the word pillbox in connection with a defensive post is from 13 September 1917.

Pillboxes (Fig 14) are often camouflaged in order to conceal their location and to maximize the element of surprise. They may be part of a trench system, form an interlocking line of defence with other pillboxes by providing covering fire to each other (defence in depth), or they may be placed to guard strategic structures such as bridges and jetties.

c. Artillery

Many artillery installations, especially for naval artillery have historically been protected by extensive bunker systems. These usually housed the crews serving the weapons, protected the ammunition against counter-battery fire, and in numerous examples also protected the guns themselves, though this was usually a trade-off reducing their fields of fire.

Artillery bunkers were often constructed for very large guns in a pre-defined location and as part of a larger system of defenses such as for a port town or a seacoast.

d. Industrial

Typical industrial bunkers include mining sites, food storage areas, dumps for materials, data storage, and sometimes living quarters. They were built mainly by nations like Germany during World War II to protect important industries from aerial bombardment. Industrial bunkers are also built for control rooms of dangerous activities, e.g. tests of rocket engines or explosive experiments. They are also built in order to perform dangerous experiments in them or to store radioactive or explosive goods. Such bunkers also exist on non-military facilities.

e. Personal

When a house is purpose-built with a bunker, the normal location is a reinforced below-grade bathroom with large cabinets. One common design approach uses fiber-reinforced plastic shells. Compressive protection may be provided by inexpensive earth arching. The overburden is designed to shield from radiation. To prevent the shelter from floating to the surface in high groundwater, some designs have a skirt held-down with the overburden.

4.7 Blast protection

Bunkers deflect the blast wave from nearby explosions to prevent ear and internal injuries to people sheltering in the bunker. While frame buildings collapse from as little as 3 psi (0.2 bar) of overpressure, bunkers are regularly constructed to survive several hundred psi (over 10 bar). This substantially decreases the likelihood that a bomb (other than a bunker buster) can harm the structure.

The basic plan is to provide a structure that is very strong in physical compression. The most common purpose-built structure is a buried, steel reinforced concrete vault or arch. Most expedient (makeshift) blast shelters are civil engineering structures that contain large buried tubes or pipes such as sewage or rapid transit tunnels. Improvised purpose-built blast shelters normally use earthen arches or vaults. To form these, a narrow (1-2 metre) flexible tent of thin wood is placed in a deep trench (usually the apex is below grade), and then covered with cloth or plastic, and then covered with 1-2 meters of tamped earth.

A large ground shock can move the walls of a bunker several centimeters in a few milliseconds. Bunkers designed for large ground shocks must have sprung internal buildings, hammocks, or bean-bag chairs to protect inhabitants from the walls and floors.

4.8 Nuclear protection

Nuclear bunkers (Fig 15) must also cope with the under pressure that lasts for several seconds after the shock wave passes, and block radiation. Usually these features are easy to provide. The overburden (soil) and structure provide substantial radiation shielding, and the negative pressure is usually only 1/3 of the overpressure.

4.9 General features

The doors (Fig 16) must be at least as strong as the walls. The usual design is a trap-door, to minimize the size and expense. To reduce the weight, the door is normally constructed of steel, with a fitted steel lintel and frame. Very thick wood also serves, and is more resistant to fire because it chars rather than melts. If the door is on the surface and will be exposed to the blast wave, the edge of the door is normally counter-sunk in the frame so that the blast wave or a reflection cannot lift the edge. A bunker should have two doors. Door shafts may double as ventilation shafts to reduce digging.

In bunkers inhabited for prolonged periods, large amounts of ventilation or air conditioning must be provided in order to prevent ill effects of heat. In bunkers designed for war-time use, manually-operated ventilators must be provided because supplies of electricity or gas are unreliable. One of the most efficient manual ventilator designs is the Kearny Air Pump. Ventilation openings in a bunker must be protected by blast valves. A blast valve is closed by a shock wave, but otherwise remains open. One form of expedient blast valve is tyre-treads nailed or bolted to frames strong enough to resist the maximum overpressure.

If a bunker is in a built-up area, it may have to include water-cooling or an immersion tub and breathing tubes to protect inhabitants from fire storms.

Bunkers must also protect the inhabitants from normal weather, including rain, summer heat and winter cold. A normal form of rainproofing is to place plastic film on the bunker’s main structure before burying it. Thick (5-mil or 0.13 mm), inexpensive polyethylene film serves quite well, because the overburden protects it from degradation by wind and sunlight.

4.10 Bailey Bridge

The Bailey bridge is a portable pre-fabricated truss bridge, designed for use by military engineering units to bridge up to 60 m (200 ft) gaps. It requires no special tools or heavy equipment for construction, the bridge elements are small enough to be carried in trucks, and the bridge is strong enough to carry tanks. It is considered a great example of military engineering.

4.11 History

Donald Bailey was a civil servant in the British War Office who tinkered with model bridges as a hobby. He presented one such model to his chiefs, who saw some merit in the design and had construction started at a slow rate. The bridge was taken into service by the Corps of Royal Engineers and first used in Italy in 1943. A number of bridges were available by 1944 for D-Day, when production was ramped up. The US also licensed the design and started rapid construction for their own use. Bailey was later knighted for his invention, which continues to be widely produced and used today.

4.12 Design

A large part of what made Bailey bridges (Fig 17 & Fig 18) as successful and unique as they were is the modular design, and the fact that it could be assembled with minimal aid from heavy equipment. Most, if not all, previous designs for military bridges required cranes to lift up the preassembled bridge and lower it into place. The Bailey parts were made of standard steel alloys, and were simple enough that parts made at a number of different factories could be completely interchangeable. Each individual part could be carried by a small number of men, enabling army engineers to move more easily and more quickly than before, in preparing the way for troops and matériel advancing behind them. Finally, the modular design allowed engineers to build each bridge to be as long and as strong as needed, doubling or tripling up on the supportive side panels, or on the roadbed sections.

The basic bridge consists of three main parts. The “floor” of the bridge consists of a number of 19 ft (5.8 m) wide transoms that run across the bridge, with 10 ft long stringers running between them on the bottom, forming a square. The bridge’s strength is provided by the panels on the sides, which are 10 ft (3 m) long cross-braced rectangles. These are placed standing upright above the stringers, and clamps run from the stringers to the panels to hold them together. Ribands are placed on top of the completed structural frame, and wood planking is placed on top of the ribands to provide a roadbed. Later in the war, these wooden panels were replaced by steel, which was more resistant to the damage caused by tank treads.

Each unit constructed in this fashion creates a single 10 ft (3 m) long section of bridge, with a 12 ft (4 m) wide roadbed. After one section is complete it is typically pushed forward over rollers on the bridgehead, and another section built behind it. The two are then connected together with pins pounded into holes in the corners of the panels.

For added strength several panels (and transoms) can be bolted on either side of the bridge, up to three. Another solution is to stack the panels vertically. With three panels across and two high, the Bailey Bridge can support tanks over a 200 ft (60 m) span.

A useful feature of the Bailey bridge is its ability to be “launched” from one side of a gap. In this system the front most portion of the bridge is angled up with wedges into a launching nose and most of the bridge is left without the roadbed and ribands. The bridge is placed on rollers and simply pushed across the gap, using manpower or a truck or tracked vehicle, at which point the roller is removed (with the help of jacks) and the ribands and roadbed installed, along with any additional panels and transoms that might be needed.

5.0 CONCLUSION

The military architecture of India was under the influence of several cultures for countless centuries. We had an indigenous system in the Indus Valley Civilisation during the ancient period after which the Aryans came who brought in a system of their own. Then by the medieval period came the Mughals. The Mughals had a very deep influence in India and their system spread along the length and breadth of the country. By the 1800’s came the British who in a way started the modernization of the military architecture of India. Indians for the major part of their history were unwilling to bring in new thoughts or redesign the existing system, whatever changes occurred were forced upon them.

Military architecture is one of the fields where the disparity between the rich and poor nations is least evident as every country is willing to shell out more than enough money to protect it self. Though some might state that we are unnecessarily spending a lot of money on this field which could have been otherwise used for alleviating poverty, it is interesting to note that some of the innovations which started as military experiments later on found civilian applications.

6.0 REFERENCES

1. Major Gurcharan Singh Sandhu, (2000), A Military History of Ancient India, Vision Books.

2. Major Gurcharan Singh Sandhu, (2003), A Military History of Medieval India – Vision Books.

3. Ratanlal Mishra, (2002), Military Architecture in Ancient India - B.R. Publishing Corporation.

4. James P. Cole and Oliver Schoonmaker, (2005) Military Instructors Manual – United States Army.

5. http://en.wikipedia.org

6. http://harappa.com

7. http://weburbanist.com/2008/04/20/creatively-converted-sea-forts-of-great-britain-strange-adaptive-reuse-of-military-architecture/

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Tags: arthashastra, bailey bridges, british, bunkers, colony, kautilya, military architecure in india, mughals, trenches