During World War II, Shaw enlisted in the United States Navy and shortly after formed a band, which served in the Pacific theater (just as Glenn Miller's wartime band served in the UK and Europe). After 18 months playing for Navy personnel, (sometimes as many as four concerts a day in battle zones, including Guadalcanal), Shaw returned to the U.S. in a state of physical exhaustion and received a medical discharge. After the war, the popularity of big bands declined, as Crooners and Bebop began to dominate the charts.