Manpower is the fundamental raw material of any army, and it is always in short supply. Start with 80 million Germans; take out the 40 million women and the 10 million male children, and you've got a pool of 30 million men. Next, remove 5 million old men, and you're down to 25 million. Now take out government workers and public servants (4 million), those who don't meet minimum physical standards (1 million) and workers in farms, war industries, and other essential servics (10 million) and you've got 10 million men for the armed forces. That may sound like a lot, but now factor in the losses they suffer. In the summer of 1944 Germany lost half a million men on the Western Front and another million on the Eastern Front. These were total losses in killed, captured, and disabled. The graduating class of new 18-year-olds numbered only half a million.

The arithmetic of death is simple and brutal: if you lose 1.5 million, and you replace half a million, that creates a shortfall of one million soldiers. How do you make up the loss? The Germans tried everything. They used foreign slave labor to replace factory workers. They put more women to work in factories and on farms. They combed out all unnecessary rear-area jobs, sending Navy and Luftwaffe troops into the Army. They lowered the physical standards for the Army, and raised the draft age to 60. They also lowered (to 16 years old) the age at which a boy could volunteer. Then they "strongly encouraged" boys to volunteer. They seldom checked a boy's claimed age; there were many 14-year-olds fighting in the German army in the Battle of the Bulge.