Final answer:
The mandated period of military service varies by country and military branch. France historically required three years of service, while the U.S. National Guard's slogan 'One weekend a month, two weeks a year' indicated a minimum, which has evolved since the Iraq War.
Step-by-step explanation:
The period of service required in the armed forces differs depending on the country and the specific regulations in place for service members. For instance, during particular periods in history, France required three years of compulsory service from all men. This can be compared with the U.S., where the period of service may vary; the slogan "One weekend a month, two weeks a year" used by the U.S. National Guard represented a basic training commitment before the Iraq War. However, after the Iraq War, nearly 28 percent of U.S. forces were from mobilized National Guard and Reserve components, with some proposing to increase annual training to up to seven weeks per year. Furthermore, for the appropriation of money for raising and supporting armies, the U.S. Constitution specifies that it shall not be for a term longer than two years, reflecting a limit on funding commitments rather than individual service terms.