In 1915, the Racine Regulars formed Wisconsin's first important semi-professional team. They primarily played against teams from Illinois and Indiana. The team became known as the Racine Battery C in 1916 after many of the players joined the First Wisconsin Reserve Artillery Battery C.
Because of World War I and the Spanish flu pandemic of 1918 the team took a break. It was reorganized in 1919 with sponsorship from the local American Legion post and William Horlick, president of his family's malted milk company. The reorganized team was known as the Horlick-Racine Legion.
In 1922, the American Professional Football Association changed its name to the National Football League. Racine, now known simply as the Racine Legion, although its official name remained the Horlick-Racine Legion, was one of four new teams admitted to membership that season.
Led by the fullback-kicker Hank Gillo, who led the league in scoring with 52 points, Racine finished sixth in the 18-team league with a 6–4–1 record. Despite two more respectable seasons, the team failed because of finances. In 1925, the franchise was held over by the NFL, but they did not field a team that season.
Milton "Mitt" Romney, team captain at the University of Chicago in 1922, became a quarterback for the Racine Legion before later joining the Chicago Bears. He was a cousin of Michigan Governor George W. Romney, and his nickname inspired that of George Romney's son, 2012 U.S. presidential candidate Mitt Romney.
Facing the threat of Red Grange's American Football League in 1926, the NFL was eager to get as many teams and players as possible into the fold to keep them away from the AFL. The Racine franchise was reactivated. The team, now called the Tornadoes, had a few of the same players as the Legion but many stars went to other teams in 1925. After winning their first game, the Tornadoes lost four in a row and disbanded in late October because of struggling finances.