Leading war poets included Siegfried Sassoon, Wilfred Owen, John McCrae, Rupert Brooke, Isaac Rosenberg, and David Jones. A similar movement occurred in literature, producing a slew of novels on both sides of the Atlantic, including notably: All Quiet on the Western Front, and Johnny Got His Gun. The 1963 English stage musical Oh, What a Lovely War! provided a satirical take on World War I, which was released in a cinematic version directed by Richard Attenborough in 1969.
The meaning of military tactics has changed over time; from the deployment and manoeuvring of entire land armies on the fields of ancient battles, and galley fleets; to modern use of small unit ambushes, encirclements, bombardment attacks, frontal assaults, air assaults, hit-and-run tactics used mainly by guerrilla forces, and, in some cases, suicide attacks on land and at sea. Evolution of aerial warfare introduced its own air combat tactics. Often, military deception, in the form of military camouflage or misdirection using decoys, is used to confuse the enemy as a tactic.
The operational level is at a scale bigger than one where line of sight and the time of day are important, and smaller than the strategic level, where production and politics are considerations. Formations are of the operational level if they are able to conduct operations on their own, and are of sufficient size to be directly handled or have a significant impact at the strategic level. This concept was pioneered by the German army prior to and during the Second World War. At this level, planning and duration of activities takes from one week to a month, and are executed by Field Armies and Army Corps and their naval and air equivalents.
Each branch of the service operates its own Service Academy as a four-year institution of higher education. All students receive a full scholarship with a small monthly stipend. Upon graduation, you're commissioned as a second lieutenant in the Army, Air Force, or Marine Corps or as an ensign in the Navy or Coast Guard. Appointment to a service academy is extremely competitive. For more information, call 1-800-822-8762 (US Military Academy in West Point, New York), 1-800-638-9156 (US Naval Academy in Annapolis, Maryland), 1-800-443-9266 (US Air Force Academy in Colorado Springs, Colorado), 1-800-883-8724 (US Coast Guard Academy in New London, Connecticut), and 1-866-546-4778 (United States Merchant Marine Academy, Kings Point, New York).
The next requirement comes as a fairly basic need for the military to identify possible threats it may be called upon to face. For this purpose, some of the commanding forces and other military, as well as often civilian personnel participate in identification of these threats. This is at once an organisation, a system and a process collectively called military intelligence (MI).