Military engineering is, in essence, civil engineering undertaken in a military environment. The duties of military engineers also include mapping and surveying, which became increasingly important as indirect fire weapons were deployed. The constraints of time, finance, labour, and materials, which affect all civil engineering projects, weigh especially heavily on military engineers in time of war, with the added complication that engineering activities may be hampered by enemy action, sometimes in conditions of actual combat. Military engineers are required not only to construct their own works, but also to destroy those of the enemy. The engineer's role in the provision of protection against intruders may be said to have begun with the construction of simple huts and walls. These gradually developed into great positional defences of earth and stone around cities and on the frontiers of states, requiring the use of skilled engineers both to design those of their own side and to attack those of the enemy. With the advent of gunpowder, the mathematical and scientific knowledge needed by engineers for fortification and siegecraft became increasingly important and most modern military academies trace their descent from schools for engineers and artillery established during the 18th century. In sieges, the engineer's duty was not merely to act as a technical expert, but also to conduct troops forward to the point of attack when a fortress was stormed. In the British army, a standard cry was ‘follow the sapper’, the term for those who, under engineer officers, dug the saps or shelter trenches used in the attack on fortresses. If the demolition of an obstacle required the use of explosives, the engineers placed the charges and ignited the fuses. Among many heroic episodes of the Indian Mutiny campaign was that of the Powder Bag party, including fourteen sepoys of the Bengal Sappers and Miners under engineer officers, who blew in the heavily defended Kashmir Gate at the British storming of Delhi. Field fortifications, generally made of local materials and intended to serve a temporary need, can be constructed and, in the case of enemy works, demolished by ordinary sappers and pioneers, who are required to possess only basic field engineering skills.
The simplest form of road in field engineering consists of two parallel ditches with the excavated spoil heaped between them to produce a cambered way. An alternative type, widely used in wooded swampy areas, is the corduroy road, made by felling trees to clear a path, splitting the trunks, and laying them transversely to form a corrugated roadway. More permanent roads, built by military engineers for strategic purposes, generally assumed a wider economic role, allowing wheeled traffic to move easily where previously only less efficient pack animals could go. Examples include the straight highways of the Roman empire, the military roads built by FM Wade and his redcoats in the Scottish Highlands after the Jacobite rebellion of 1715, and the Grand Trunk Road, 1, 500 miles (2, 414 km) long, in British India. In many cases, such roads continued as public highways for hundreds of years after they had served their original military purposes. Away from the combat area, military engineers assumed the role of architects, designing barracks and camps complete with buildings for every kind of function, including housing for officers and men, kitchens and dining halls, offices, stores, workshops, stables and wagon lines, guardrooms, hospitals, schools, churches, etc., together with roads and exercise grounds. During the 19th century, as European and American governments extended their dominions into areas of previously untamed wilderness, it was frequently the case that the only engineers available for the construction of public works were those belonging to the military. Such employment was readily sought by engineer officers, who not only had the personal satisfaction of opening up new terrain, but were also able to practise their profession in conditions similar to those of actual campaign. In the USA, the Corps of Engineers assumed, and retained, responsibility for the construction and maintenance of navigations and waterways in parts of the country long under civilized occupation. The draining of morasses, a skill in which all military engineers were trained in order to counter enemy inundations, was especially valuable in such areas.
Bridge-building, especially over rivers and watercourses across which armies have to pass, has been a vital element of military engineering from the earliest times. Bridges made of boats collected together and moored side by side, with a decking of timber planks, were used from the classical period. Xerxes crossed the Hellespont (Dardanelles) by this method in 480 bc. Pontoon bridges are constructed on the same principle, with the pontoons (light boats designed to be transported overland) acting as floating piers, on which the planking carried as an integral part of their bridging train is laid. In the absence of pontoons, rafts, barrels, or inflated skins could be used for flotation. ‘Flying bridges’, used in the campaigns of Alexander ‘the Great’ and still familiar to military engineers in the early 20th century, were made by anchoring boats (usually covered by decking) to a point in mid-river. They were moved from one bank to another by angling the bows into the current. Shallow rivers and dry gullies could be bridged by lines of wagons, and with the advent of motorized transport a similar role was assumed by tracked vehicles. A standard technique for crossing ditches, moats, etc, was to build a causeway using brushwood, earth, or rocks. The application to warfare of modern industrial and scientific developments added new fields of science and technology to military engineering. In operational areas, military engineers built and ran railways. Telegraph, radio, chemical and biological weapons, and aviation were all originally allotted by armies to their engineers, before the formation of specialist corps.
Bibliography
- Douglas, Howard, An Essay on the Principles and Construction of Military Bridges and the Passage of Rivers in Military Operations (London, 1853).
- Kerry, A. J., The History of the Corps of Royal Canadian Engineers (Ottawa, 1962).
- Smithers, A. J., Honourable Conquests: An Account of the Enduring Work of the Royal Engineers throughout the Empire (London, 1991)
— Tony Heathcote
