Kiesling began his coaching career at age 34 during the 1937 season as an assistant coach under Johnny Blood for the Pittsburgh Pirates (renamed the Steelers in 1940). He was also a player for the Pirates during the 1937 and 1938 seasons, appearing in a total of 12 games. When Blood resigned as head coach after the team lost the first three games of the 1939 season, team owner Art Rooney hired Kiesling as the team's new head coach. Kiesling led the Pirates to a 1–6–1 record in the final eight games of the 1939 season. Kiesling led the Steelers to a 2–7–2 record during the 1940 season and was replaced by Bert Bell and Aldo Donelli in 1941. Kiesling resumed his role as head coach near the end of the 1941 season, leading the team to a 1–2–1 in the final four games. Kiesling led the 1942 Steelers to a 7–4 record, the first winning season in club history since the team was formed in 1933. Kiesling's 1942 team was led on the field by rookie halfback Bill Dudley who totaled 1,138 yards of total offense (696 rushing and 438 passing) and also had 576 yards on punt and kickoff returns. Dudley was drafted into Army after the 1942 season. In 1943, with so many players lost to military service, the Steelers were temporarily merged with the Philadelphia Eagles to form the Steagles. Kiesling and the Eagles' coach Greasy Neale served as co-coaches of the Steagles. The Steagles compiled a 5–4–1 record. In 1944, the Steelers were still lacking players due to the war and formed a one-year merger with the Chicago Cardinals, operating under the name Card-Pitt. Kiesling and the Cardinals' coach Phil Handler served as co-coaches. Despite the play of John Grigas, a Cardinals back who led the NFL in 1944 with 1,154 all-purpose yards and 471 kickoff return yards, the Card-Pitt team gave up 32.8 points per game, compiled a 0–10 record, and was outscored by a combined total of 328–108. Green Bay Packers In January 1945, Kiesling resigned as the Steelers' coach. Hours after resigning his position with the Steelers, Kiesling was hired as assistant coach for the Green Bay Packers. He coached the Packers' linemen, and in December 1945, he signed a contract extending his service through the 1947 season. In January 1948, his contract was renewed again through the 1948 season. At the