The Federal League of Base Ball Clubs, known simply as the Federal League, was an American professional baseball league that played its first season in 1913 and operated as a "third major league", in competition with the established National and American Leagues, from 1914 to 1915.
The Federal League came together in early 1913 through the work of John T. Powers, and immediately challenged the operations of organized baseball. Playing in what detractors called the "outlaw" league allowed players to avoid the restrictions of the organized leagues' reserve clause. The competition of another, better paying league caused players' salaries to skyrocket, demonstrating the bargaining potential of free agency for the first time.
Interference by the National and American Leagues in their operations caused the Federal League to fold after the 1915 season. This resulted in a landmark federal lawsuit, Federal Baseball Club v. National League, in which the U.S. Supreme Court ultimately ruled that the Sherman Antitrust Act did not apply to Major League Baseball. The Federal League left its mark on baseball history in the field now known as Wrigley Field, which was originally built for the Chicago Whales Federal League team. The league itself and many sports writers considered it a major league during its existence; organized baseball recognized its major league status in 1968. It would be the last independent major league outside the established structure of professional baseball to actually make it to the playing field, and would be the last serious attempt to create a third major league until the abortive Continental League of 1960.