Marching

Marching refers to the organized, uniformed, steady walking forward in either rhythmic or route-step time; and, typically, it refers to overland movements on foot of military troops and units under field orders. It is a major part of military basic training in most countries and usually involves a system of drill commands. A soldier learning to march to drum cadences, martial music and shouted commands is considered an essential element of teaching military discipline.
Marching is often performed to march music and is typically associated with military and civilian ceremonial parades.
For rhythmic marching, individuals must maintain their "dress", "cover", "interval", and "distance" (DCID):
In Northern Ireland, for some people, marching is a major provocative ritual. Hundreds of marches occur annually. These are usually organized by groups such as the Orange Order, which provide most of the participants. Music is provided by marching bands including silver bands, flute bands and others. Marching is often seen as a symbol of control over a particular area, and marching is often seen as a sectarian activity.
The Royal Marines refer to a long distance march carrying full kit as a yomp. The most famous yomp of recent times was during the 1982 Falklands War.
Military paces.
In the military venue there are various rhythmic military steps or standard paces. One step occurs on each beat. A pace is the length of one step, assumed to be 75 cm or 30"; (not to be confused with the ancient Roman unit of length (2 steps or 5 Roman feet = 148 cm or 58")).
For mechanical efficiency, opposite arms usually swing with each leg while marching.
British and Commonwealth armed forces keep their arms straight and swing the hand as high as the shoulder while forward and in theory to the level of the belt when backward. US Marines swing the arm six inches to the front and three inches to the rear while US Army Soldiers swing the arm nine inches to the front and six inches to the rear. Some European armies bend the arm during the swing. Most foot drill instructors believe these differing practices are efficient i.e. maintain rhythm for long route marches. US troops usually march long distances at "route step" which does not require them to maintain a specific pace or length of step. Some South American and Eastern European countries march on parade with the stiff leg earlier famous as the "goose step" of German troops. German and Scandinavian military bands and units swing with only the right arm, 90 degrees straight out. Some troops (like the Royal Swedish Lifeguard) swing with their left arm. This is because they carry their rifle in their right arm.