Original: After the attack on Pearl Harbor, Jolson became the first star to entertain troops overseas during World War II, and again in 1950 became the first star to perform for G.I.s in Korea, doing 42 shows in 16 days.
Simplified: After the attack on Pearl Harbor, Jolson became the first star to entertain troops overseas during World War II. Again in 1950 became the first star to perform for GIs in Korea.