Knowles was first elected to the Wisconsin State Senate in 1941, becoming Majority Leader after only two years in office in 1943, but during World War II he took a break to serve as a lieutenant in the U.S. Navy aboard the USS Nevada.[REF]
Knowles's brother, Robert P. Knowles, served as President Pro Tempore of the Wisconsin State Senate during his last two terms as Governor and during the first four years of Governor Patrick Lucey's administration from 1967 to 1975.