Just under 17,000 men entered service in November and December 1940 with another 259,000 between January and March I941, the majority arriving untrained to increase Regular Army units to wartime authorizations. Later, inductees filled the National Guard divisions and, after Pearl Harbor, they formed Organized Reserve divisions. By mid-I941, basic training was consolidated in replacement centers with tactical units drawing their personnel from the centers.1
On August I8, 1941, President Roosevelt extended the inductees' period of service to I8 months, releasing those aged 28 and older [This affected Dad] G.B. , although most were called back to duty after Pearl Harbor. On February 16, 1942, 20 year-olds began registering and shortly thereafter started to be drafted. The Draft was in full swing; in 1942, 3,564,000 inductees entered the Army, more than in any other year of the war.1
By June 30, 1942, I8- and I9-year-olds were registered, becoming liable for service shortly thereafter, with 19 year-olds drafted first. However, by the end of 1942 there were still more soldiers aged over 40 than under 20 on active duty. 1
By 1942, the SSS moved away from administrative selection by its more than 4,000 local boards to a system of lottery selection. Rather than filling quotas by local selection, the boards now ensured proper processing of men selected by the lottery. This facilitated the massive requirement of up to 200,000 men per month and would remain the standard for the length of the war. The WWII draft operated from 1940 until 1947 when its legislative authorization expired without further extension by Congress. During this time, more than 10 million men had been inducted into military service. 2
1 - Excerpts from the book "US Infantrymen in World War II (3) European Theater of Operations 1944-45" by Robert S. Rush.