Unlike the other belligerents, the United States had made virtually no military preparations for war on the scale that armed conflict developed starting in 1914. The country not only lacked a large army, it also had no plans for massive mobilization, and even the small army it had in hand—less than 130,000 officers and men augmented by 180,000 in the National Guard—was scattered and poorly trained. Only in the navy, comprised of some 60,000 men and 300 ships, did the United States have a force capable of rapid application.- The need to man a large army and navy, and to do it quickly, convinced a reluctant President Wilson to adopt conscription. In a major policy shift from the traditional American reliance on voluntarism to fill the ranks. Congress passed the Selective Service Act authorizing a universal conscription policy to meet any manpower needs during war or a national emergency. Through local draft boards, the government registered 24 million men between the ages of eighteen and forty-five. Almost 3 million American males found themselves called into military service. More than 1.5 million more volunteered. For most of them, military service brought a new acquaintance with distant parts of the country and fellow soldiers from other groups in the population. In the 42nd (Rainbow) Division, for example, troops from twenty-six states and the District of Columbia served together. The army also was the venue for furthering Wilson's and the Progressives' social reforms. The anti-venereal disease and anti-prostitution campaigns the Progressives had launched in American cities now went to the army camps. Soldiers were warned that "a German bullet is cleaner than a whore." To the consternation of segregationist politicians from the South like Senator James Vardaman of Mississippi, roughly 400,000 African Americans served in the military. Although blacks were confined to segregated units and often left to do fatigue duty such as hauling goods and trash removal, two black divisions did reach the front. The 92nd Division fought as a unit under American command. Its performance was roundly condemned by white senior officers, although its problems stemmed in part from poor training and inadequate leadership. Regiments of the 93rd Division, however, saw combat as part of the French army and fought valiantly. For over 2 million young Americans, conscription meant a personal encounter with European life as well as the threat of death or injury in combat. Processing young Americans for military service produced information on the population that no one had possessed before. Some was highly disturbing: doctors examining the recruits found that almost 30 percent were physically unable to meet the standards for military service. During World War I social scientists and medical doctors conducted the first mass testing of Americans as to "intelligence." Using the recendy developed Binet intelligence test — which later scientists showed to have been skewed in favor of western European cultures, among other defects—the testers "confirmed" many popular stereotypes about the "inferiority" of blacks and southern and eastern European groups. Armed with such "scientific" data, racists and nativists called for restrictions on blacks and limits on immigration.