History of JROTC:

The United States Army Junior Reserve Officers' Training Corps (JROTC) came into being with the passage of the National Defense Act of 1916. Under the provisions of the Act, high schools were authorized the loan of federal military equipment and the assignment of active duty military personnel as instructors. In 1964, the Vitalization Act opened JROTC up to the other services and replaced most of the active duty instructors with retirees who worked for and were cost shared by the schools.

Title 10 of the U.S. Code declares that "the purpose of Junior Reserve Officers' Training Corps is to instill in students in United States secondary educational institutions the value of citizenship, service to the United States, personal responsibility, and a sense of accomplishment."

http://www.cadetcommand.army.mil/jrotc-history.aspx