New recuits got an occasional fatherly pat on the back, but being indoctrinated into the military was hardly a family picnic at the park. There was exercise and long marches and drilling. And more exercise.

A bunch of recruits make their way through the long and not-very-private process of getting checked out to ensure they are physically capable of enduring the rigors of training and combat. (National Archives)

In 1939, the US military counted 356,000 men and women in its ranks. During World War II, 16 million were churned through the recruiting process. (National Archives)

Like automobiles on a production line, new enlistees collect the bits and pieces of equipment that will be integral parts of their new lives for the duration of their term of service or their lives, whichever would come first. The process may not have been pretty, but it pumped out a massive armed force, seemingly from thin air, in a very short time. (National Archives)

The transition from civilian to soldier, sailor, or marine was not instant, but the shift from civilian to “boot” went quickly. You stepped off the bus or train, and before you knew it, you had been shorn, issued a lot of unfamiliar clothing, and piled into a barracks full of strangers. (National Archives)

The idea of getting into tip-top shape was not to make recruits look good in uniform. It was intended to make them deadly. I could save their lives, and the lives of their comrades in arms. (National Archives)

Physical training had the obvious benefit of strengthening the bodies and resolution of the recruits. More subtly, it taught them to do things in unison, as a team. (National Archives)

A young man spent his early weeks in the service staring at the back of another man’s head, while trying to keep cadence during strenuous workouts. For many men, the physical side of things was the easy part. There were also rules to memorize and skills to perfect. (National Archives)

To get the massive number of recruits trained and into action, Uncle Sam needed a lot of training camps. The marines whipped recruits into shape at San Diego and Parris Island, South Carolina. Coast Guardsmen learned the ropes on Government Island at Alameda, California, at Curtis Bay, Maryland, and in St. Augustine, Florida. Navy swabbies turned up en masse at Norfolk, Virginia, and San Diego and a few other locations. The army, the largest of the services, ran 118 training centers across the country. (National Archives)

Recruits training on an obstacle course usually carried their trusty M1 Garand rifles. The weapon weighed about 10 pounds, and felt much heavier by the end of the day. (National Archives)

By the end of training, recruits felt that their rifles were almost part of their own anatomy. With its eight-shot clip and high degree of accuracy, the Garand M1 was a nightmare to opposing forces when wielded by a skilled shooter. (National Archives)

It was said that the 30.06-caliber bullet from the M1 could kill three enemy soldiers in a single shot, passing through one and another before running out of steam in the third. General George S. Patton called the Garand “the greatest battle implement ever devised." US military forces used the rifle from 1937 through the mid-1960s. (National Archives)

Nobody ever said it was going to be easy! Recruits trained to do all sorts of things with full packs, bayonets, M1, and plenty of ammo clips. Being able to scramble along ropes or vines gave men a whole new idea of what the word “tough” meant. (National Archives)

Recruits learned in training that a disarmed soldier is not necessarily out of the fight. (National Archives)

In the hedgerows of Europe and the jungles of Asia and the Pacific islands, a lot of the fighting was man to man. Part of the training of a recruit was learning to put another man on the ground before the same could be done to him. (National Archives)

US Navy recruits at Naval Air Station Corpus Christi, Texas, on October 9, 1942, ship-shape and standing in the all-to-familiar queue. The US government accomplished the miraculous during the course of the war, starting with a skeleton force and ending with a military jugernaut worthy of a superpower. (National Archives)