On June 18 1970
June 18, 1970: Southern California wins the first of five straight Division I Baseball Championship titles under coach Rod Dedeaux (who coached the Trojans to a total of 10 titles between 1958 and 1978).
Sources:
Sources: “In the Arena: The NCAA’s First Century” by Joseph N. Crowley, NCAA News and Champion magazine archives, the NCAA Media Center, and NCAA record books