A military parade (square bashing in British military slang) is a formation of soldiers whose movement is restricted by close-order manoeuvring known as drilling or marching. The American usage is "formation or military review". The military parade is now almost entirely ceremonial, though soldiers from time immemorial up until the late 19th century fought in formation. Massed parades may also hold a role for propaganda purposes, being used to exhibit the apparent military strength of one's nation.
The terminology comes from the tradition of close order formation combat, in which soldiers were held in very strict formations as to maximise their combat effectiveness. Formation combat was used as an alternative to mêlée combat, and required strict discipline in the ranks and competent officers. As long as their formations could be maintained, regular troops could maintain a significant advantage over less organised opponents.
Although the firepower of breechloading rifles and machine guns long ago rendered close formations in battle suicidal, modern armies still use parades for ceremonial purposes or in non-combat environments for their efficiency, ease of organization and encouragement of discipline. Roughly synonymous are "drill" and "march". The English word "drill" is of Middle Dutch origin, dating from the 16th century drill of the Dutch army of prince Maurice of Orange, which was widely copied throughout Europe at the time.