Starting as a versatile athlete in the early 1900s, Halas soon transitioned to coaching, leading teams with his innovative strategies and fierce competitiveness. He co-founded the Decatur Staleys (later renamed the Chicago Bears) in 1920, becoming owner, coach, and even player at times. He revolutionized the game with tactics like the T-formation and the "man in motion," forever changing the offensive landscape.

Halas wasn't just building a team; he was building a league. He was pivotal in establishing the National Football League (NFL) in 1920, serving as its president for multiple terms and shaping its rules and structure. He was a shrewd businessman, securing television deals and driving the league's financial growth.

His influence extended beyond the field. He advocated for player safety, fought for racial equality, and even served as a Navy officer during World War II. He became a symbol of integrity and leadership, earning the respect of players, coaches, and fans alike.