Final answer:
The enlistment period for soldiers varied based on the time period and nation's military policy. Compulsory service lengths ranged from a few years in some countries to potentially open-ended service in times of war or national emergency. Military service terms were also affected by social and racial factors, with some soldiers facing segregation or discrimination.
Step-by-step explanation:
The length of enlistment for presidio soldiers has varied greatly throughout history and depended on the specific time period and national military policies in place. For example, during the early days of the United States, the Continental Army started allowing the enlistment of all free blacks in 1777 to fill its depleted ranks. Similarly, during World War II, the Tekketsu Kinnōtai, a group of middle school boys aged 14-17 years, were mobilized by the Imperial Japanese Army into front-line-service. Meanwhile, the French military at the time required three years of compulsory service from all men, with reservists ready to be mobilized as well. In the United States, the 442nd Regimental Combat Team, which included many second-generation Japanese Americans, became one of the most highly decorated units in US military history. The term of service for soldiers has also been influenced by larger geopolitical and social issues, such as racial segregation and the challenges that immigrant soldiers faced.