1918 Boston Red Sox season

American League champions The 1918 Boston Red Sox season was the 18th season in the franchise's Major League Baseball history. The Red Sox finished first in the American League (AL) with a record of 75 wins and 51 losses, in a season cut short due to World War I. The team then faced the National League (NL) champion Chicago Cubs in the 1918 World Series, which the Red Sox won in six games to capture the franchise's fifth World Series. This would be the last World Series championship for the Red Sox until 2004.

With World War I ongoing, a "work or fight" mandate was issued by the government, requiring men with non-essential jobs to enlist or take war-related jobs by July 1, else risk being drafted. Secretary of War Newton D. Baker granted an extension to MLB players through Labor Day, September 2. In early August, MLB clubs decided that the regular season would end at that time. As a result, AL teams played between 123 and 130 regular-season games (including ties), reduced from their original 154-game schedules. Later in August, Baker granted a further extension to allow for the World Series to be contested; World War I would end two months later, with the Armistice of 11 November 1918.

Due to the entry of the United States into World War I, several Red Sox players enlisted with the military over the winter. Notable players who enlisted included Pitchers Ernie Shore and Herb Pennock, Outfielder Duffy Lewis, as well as Manager Jack Barry.

The Red Sox' pitching staff, led by Carl Mays and Bullet Joe Bush, allowed the fewest runs in the league. Babe Ruth was the fourth starter and also spent significant time in the outfield, as he was the best hitter on the team, leading the AL in home runs and slugging percentage.

After this season the Red Sox would fall into mediocrity as they traded away most of their star players to other teams, most notably sending Ruth to the Yankees in 1920. The team would not have another winning record until 1935, 18 years later.