After the Nazi invasion of Poland on September 1, 1939, triggered World War II, the military value of the CPTP became obvious, even to the program's detractors. The United States started to evaluate its ability to fight an air war and the results were appalling. Pilots, instructors, and training aircraft were all in short supply. Acknowledging the shortage of trained pilots, both the Army Air Corps and Navy reluctantly waived certain “elimination” courses for CPTP graduates and allowed them to proceed directly into pilot training.