World War I began in 1914, though the United States did not join until 1917 when it needed larger forces. Over 2 million African Americans registered for the draft during World War I, with 367,000 called into service both stateside and overseas. The National Association for the Advancement of Colored People advocated for equal treatment of African American soldiers during World War I and worked to boost their morale. Despite facing discrimination, African American units such as the 369th Infantry Regiment, known as the "Harlem Hellfighters", served with distinction in Europe.