Military engineering is loosely defined as the art, science, and practice of designing and building military works and maintaining lines of military transport and communications. Military engineers are also responsible for logistics behind military tactics. Modern military engineering differs from civil engineering. In the 20th and 21st centuries, military engineering also includes other engineering disciplines such as mechanical and electrical engineering techniques.
According to NATO, "military engineering is that engineer activity undertaken, regardless of component or service, to shape the physical operating environment. Military engineering incorporates support to maneuver and to the force as a whole, including military engineering functions such as engineer support to force protection, counter-improvised explosive devices, environmental protection, engineer intelligence and military search. Military engineering does not encompass the activities undertaken by those 'engineers' who maintain, repair and operate vehicles, vessels, aircraft, weapon systems and equipment."
Military engineering is an academic subject taught in military academies or . The construction and demolition tasks related to military engineering are usually performed by military engineers including soldiers trained as sappers or pioneers. In modern armies, soldiers trained to perform such tasks while well forward in battle and under fire are often called combat engineers.
In some countries, military engineers may also perform non-military construction tasks in peacetime such as flood control and river navigation works, but such activities do not fall within the scope of military engineering.
The word engineer was initially used in the context of warfare, dating back to 1325 when engine’er (literally, one who operates an engine) referred to "a constructor of military engines". In this context, "engine" referred to a military machine, i. e., a mechanical contraption used in war (for example, a catapult).
As the design of civilian structures such as bridges and buildings developed as a technical discipline, the term civil engineering entered the lexicon as a way to distinguish between those specializing in the construction of such non-military projects and those involved in the older discipline. As the prevalence of civil engineering outstripped engineering in a military context and the number of disciplines expanded, the original military meaning of the word “engineering” is now largely obsolete. In its place, the term "military engineering" has come to be used.