Ted Williams is best known as one of the greatest hitters in baseball history. He also served in the Navy and Marines during World War II and the Korean War. He was also an avid sport fisherman. For detailed information, read the Wikipedia article.
Ted Williams played his entire baseball career with the Boston Red Sox. He played from 1939-1942 and from 1946-1960. He was a 17 time All-Star, 2 time AL MVP, 6 times AL batting champ, and 2 time Triple Crown winner. He ended his career with a .344 batting average, 521 home runs, and .482 on base percentage. In 1941 he finished the season with a .406 batting average. He is the last player to finish with an average over .400.
Ted retired in 1960 and was voted into the hall of fame in 1966(his first year of eligibility). He also managed the Washington Senators and Texas Rangers from 1969 to 1972.
For more about his baseball career, you can go to this section of the Wikipedia page.
In May of 1942, Ted Williams enlisted in the US Navy Reserves. Rather than playing baseball on the service teams, he opted to enroll in the aviator program. He excelled in his training and in 1944 received his Naval Aviator Wings and was commisioned a second lieutenant in the Marine Corps. He was released from active duty in 1946, but remained in the reserves.
In 1952, Ted was recalled to active duty to serve in the Korean War. After flying in various missions, he resumed his baseball career in 1953.
For more about his military service, you can go to this section of the Wikipedia page.