Note: What is a Military Occupational Specialty (MOS)? Why did the U.S. military adopt it for personnel management?

A Military Occupational Specialty (MOS)is a qualification in military personnel management that indicates an individual possesses the knowledge, skills, physical abilities, and psychological aptitude to perform a specific job. In the military, various duties are categorized as specialties based on their content, complexity, and level of responsibility, and personnel must possess the necessary specialty for their assigned role. This system was originally introduced by the U.S. military during World War II, devised out of a necessity to properly manage the large numbers of personnel mobilized. This article explains the historical context behind why it was adopted.

The United States entered World War II in 1941 and, through large-scale mobilization, became an organization with 12.35 million personnel. The U.S. Army, in particular, faced the need to manage a vast number of personnel, which was an extremely complex task. One of the problems the U.S. Army faced at the time was that there was no efficient way to identify individuals with the aptitude for combat among a diverse pool of personnel in terms of physical strength, intelligence, and skills.

The U.S. Army began mobilization in 1942 and completed it in 1943. During this period, the assignments of many personnel were determined based on physical examinations, intelligence test results, and work history derived from occupational classification. For example, a driver with a license for large vehicles would be assigned to a transportation unit and given the duty of a large vehicle driver. While this method worked to some extent, it gradually became clear that it was difficult to identify individuals with the aptitude for roles that had no equivalent in the civilian sector, such as infantry.

A modern infantryman needed to master at least ten different types of weapons and also learn basic knowledge such as camouflage and concealment, mine clearance, map reading, first aid, and survival skills. Needless to say, they also had to possess superior physical qualities. When trying to determine the aptitude of non-commissioned officers and officers to lead infantry units, the requirement for tactical ability was also an issue. At the time, no method for judging the quality of tactical ability had been established, making it difficult to evaluate what kind of work history made an individual suitable.

Initially, mountaineers were cited as having the appropriate skills for the infantry, but since such individuals were extremely rare in the civilian sector, it was impossible for the Army to meet the required military numbers. Furthermore, it was discovered that workers who had held highly specialized jobs in the civilian sector tended to perform well in terms of physical and intellectual ability, so when assignments were decided based on work history, it was found that excellent personnel tended to be excessively concentrated in specific types of units. It was also found that, regardless of their actual ability, white-collar workers in professions with little demand in the military, such as teachers, piano tuners, and bookkeepers, were often assigned as infantry, and the problems of personnel management based on work history became clearly recognized.

In 1942, the U.S. military implemented a major reform to solve this problem, conducting a detailed job analysis and systematizing specialties.

Every specialty was assigned a number from 001 to 999, with numbers below 500 indicating that the specialty corresponded to a civilian occupation. For example, 014 was assigned to automotive mechanics and 405 to office typists. Specialties assigned numbers of 500 or higher were specialized for military service; for example, riflemen were assigned 745 and anti-tank gunners 610. By classifying all specialties with these numbers and clarifying the authorized number of specialty holders required for each unit in the Tables of Organization, it became easy to identify how many specialty holders were lacking overall. This system not only helped with military personnel management but also proved effective in streamlining the planning and implementation of education and training.

For a nation conducting war to successfully mobilize its military, it is necessary to meet military requirements. However, as this case shows, relying on ad-hoc personnel management to fill numbers can lead to mismatches between jobs and abilities, or chronic personnel shortages in specific roles, which can hinder the exertion of combat power. The importance of a system that utilizes limited human capital as effectively as possible as an organization is something that can be said not only for the military but for all organizations.

References

Palmer, R. R., et al. 1948. The Procurement and Training of Ground Combat Troops, Washington, D.C.: Department of the Army. (PDF file)

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