For thousands of years, military forces worldwide have maintained a strict rank to keep order under the stress of battle. Even when guns are quiet, a clear-cut military hierarchy is essential to make things run efficiently, similar to the purpose of rank in businesses. The rank structure of an organized military is one of its defining characteristics and serves a number of purposes.

Maintaining Order

Due to the hazardous and often unpredictable nature of military service, a great deal of discipline is required to ensure that soldiers don't panic in the heat of combat. To build and maintain this discipline, newer soldiers often need direction and correction from more experienced members of the military. To do this, soldiers are assigned ranks according to their combat experience or training. Experienced soldiers command less experienced ones of lower rank. Higher-ranking soldiers use their authority to enforce discipline and help ensure order.

Levels of Responsibility

Much like in the civilian world, the military also uses rank structure to assign levels of responsibility. Soldiers of lower rank are equivalent to entry-level employees, while higher-ranked enlisted members are equivalent to mid-level managers in charge of day-to-day operations. Commissioned officers, meanwhile, are more like corporate management and direct the force on a larger scale. This division of responsibility ensures that the most experienced soldiers take on the most complicated roles and that all members contribute to the overall mission according to their qualifications.

Continuation of Command

Serving in the military is unlike most professions in that, on the battlefield, managers and commanders can be killed or captured at any moment. In this instance, without a concrete chain of command, less experienced soldiers would be left without direction. They might then face the prospect of death or capture themselves. To counteract this, the military uses its rank structure to assure that someone is in command at all times. For example, if a general is shot on the battlefield, the next highest-ranking officer takes his place in command.

Performance Evaluation

Many military forces also use rank and promotions as a benchmark for evaluating performance. For instance, the United States Air Force often promotes members through its junior enlisted and officer ranks very quickly. However, as members take on greater levels of responsibility, promotions to higher ranks such as master sergeant for enlisted personnel or lieutenant colonel for officers are harder to attain. Only those with the most impressive credentials earn higher promotions, while the rest do not and eventually are forced out of the service. For example, U.S. Air Force officers who are passed over twice for promotion to captain, major or lieutenant colonel are separated from the service.

The Prestige of Rank

While the main purpose of rank is to give authority by lawful means, it also accomplishes the same task psychologically. Because higher ranks are difficult to achieve, earning one of these promotions comes with a certain amount of prestige. For example, a junior enlisted member is legally required to obey the orders of a brigadier general. However, since selection to brigadier general is so competitive, many soldiers would be extra-willing to try to please a general simply because of his status.