The most recent league to challenge the National League and the American League, the Federal League was the third major league in 1914 and 1915. Many would say the league's most lasting contribution to baseball is the ballpark now known as Wrigley Field (then called Weeghman Park), where the league's Chicago Whales played. Two lawsuits launched in association with the FL were also important for baseball history, one by bringing Kenesaw Landis to the attention of the owners and one by establishing the majors' anti-trust exemption.
The Federal League began play in 1913 as a six-team minor league. The league expanded to eight clubs for the 1914 season and declared war on the other two major leagues. Federal League clubs lured away stars from the established leagues. The league's Chicago Whales signed future Hall of Famer Joe Tinker, the St. Louis Terriers picked up star hurler Three Finger Brown, and Buffalo lured first baseman Hal Chase away from the Chicago White Sox in midseason. The 1914 season featured respectable crowds and a close pennant race. It wasn't until the last day of the season that the Indianapolis Hoosiers secured the flag over the Chicago Whales. The Hoosiers lineup featured star outfielder Benny Kauff, who led the league in hitting (.370) and stolen bases (75). Dutch Zwilling hit a league leading 15 home runs for the Whales, and his teammate Claude Hendrix led the circuit with 29 victories.
In January 1915, the Federal League filed an antitrust suit against organized baseball. In the meantime, they continued luring away their stars. The St. Louis Terriers added hurler Eddie Plank, the Baltimore Terrapins picked up pitcher Chief Bender, first baseman Ed Konetchy joined the Pittsburgh Rebels, and the Brooklyn Tip-Tops signed second baseman Lee Magee from the St. Louis Cardinals. Due to poor finances, the 1914 champion Indianapolis Hoosiers sold star outfielder Benny Kauff to the Tip-Tops, and the club relocated to Newark, NJ. The 1915 season featured a close three team race for the pennant, and going in to the final day of the season, just one game separated the Chicago Whales, the St. Louis Terriers, and the Pittsburgh Rebels. Chicago ended up winning the title, .001 ahead of second place St. Louis, and just a half game ahead of third place Pittsburgh. Kauff again led the league in hitting (.342) and stolen bases (55). Buffalo's Hal Chase had a league-high 17 home runs, and the Whales' George McConnell paced all pitchers with 25 wins.
After the season, a peace treaty was signed between the Federal League and major league baseball. The Federals' lawsuit- which had been stalled by Judge (and future Commissioner) Kenesaw Landis in the hopes of provoking a settlement- was dropped. In exchange, owner Charles Weeghman of the Whales was allowed to purchase the Chicago Cubs (and move the club into Weeghman Park, later known as Wrigley Field), and St. Louis Terriers owner Phil Ball was permitted to buy the St. Louis Browns. The other owners were offered a cash settlement. The players from the other six clubs were sold to the highest bidders.
The only holdouts in the settlement were the owners of the Baltimore Terrapins, who desperately wanted to return major league baseball to their city. They launched a separate anti-trust lawsuit against the established major leagues and the other Federal League owners who had accepted the settlement. This resulted in the famous Federal Baseball ruling, in which the Supreme Court ruled that baseball did not constitute interstate trade and consequently wasn't subject to federal anti-trust law.
- Samuel A. Alito, Jr.: "The Origins of the Baseball Antitrust Exemption: Federal Baseball Club of Baltimore, Inc. v. National League of Professional Baseball Players", in The Baseball Research Journal, SABR, Volume 38, Number 2 (Fall 2009), pp. 86-93.
- Daniel R. Levitt: The Battle that Forged Modern Baseball: The Federal League Challenge and Its Legacy, Ivan R. Dee Publishers, Chicago, IL, 2012.
- David Mandell: "Did the Federal League Have a Reserve Clause?", in The National Pastime, SABR, Volume 28 (2008), pp. 104-105.
- Marc Okkonen: The Federal League of 1914-1915: Baseball's Third Major League, SABR, Cleveland, OH, 1989. ISBN 978-0910137379
- Steve West and Bill Nowlin, eds.: Whales, Terriers, and Terrapins: The Federal League 1914-15, SABR, Phoenix, AZ, 2020. ISBN 978-1-970159-21-9
- Robert Peyton Wiggins: The Federal League of Base Ball Clubs: The History of an Outlaw Major League, 1914-1915, McFarland, Jefferson, NC, 2009.