Conscription in the U.S. is know as the "draft" and also more formally as the "Selective Service Act". Conscription was used to fill vacancies when there were not enough volunteers for the military. The Military and Service Act required all males between the ages of 18-26 to register and compelled, a polite way of saying "forced" males into military service when needed during times of war and necessity. During the Vietnam War in the 1960's and 70's, numerous individuals rebelled and burned their "draft cards" which had stated their requirement in joining the military through a lottery system. To this day the system of a draft exists and all males must register upon turning 18 and be available, if called upon, for training until 39 years of age.