The early twentieth century was a time in which the rising incidence of disability related to industrial accidents, tuberculosis, World War I, and mental illness brought about an increasing social awareness of the issues involved. The entry of the United States into World War I was also a crucial event in the history of the profession. Up until this time, occupational therapy had been concerned primarily with the treatment of people with mental illness. However, U.S. involvement in the Great War and the escalating numbers of injured and disabled soldiers presented a daunting challenge to those in command. The military enlisted the assistance of NSPOT to recruit and train over 1,200 "reconstruction aides" to help with the rehabilitation of those wounded in the war. With entry into World War II and the ensuing skyrocketing demand for occupational therapists to treat those injured in the war, the field of occupational therapy underwent dramatic growth and change. Occupational therapists needed to be skilled not only in the use of constructive activities such as crafts, but also increasingly in the use of activities of daily living.