In the 1915 World Series, the Boston Red Sox beat the Philadelphia Phillies four games to one.

In their only World Series before 1950, the Phillies won Game 1 before being swept the rest of the way. It was 65 years before the Phillies won their next Series game. The Red Sox pitching was so strong in the 1915 series that the young Babe Ruth was not used on the mound and only made a single pinch-hitting appearance.

Arrangements for the Series were made on October 2, 1915 in a meeting of the team owners, league presidents, and National Commission at The Waldorf-Astoria Hotel in New York City. Red Sox owner Joseph Lannin lost the coin toss and Phillies owner William F. Baker chose to have the first two games of the Series in Philadelphia. The league presidents selected the umpires and it was announced that J. G. Taylor Spink would be one of the official scorers.

One controversy surrounded the allocation of tickets to the Red Sox' Royal Rooters fan club. Each visiting team was allocated 200 tickets; the Red Sox requested an additional 400 on behalf of their supporters. The Phillies' Baker Bowl sat only 20,000 and William Baker refused to allocate additional tickets for visiting fans. The matter was resolved when National Commission chairman Garry Herrmann chose to give the Red Sox tickets from the National Commission's Series allocation.

The World Series is the annual championship series of Major League Baseball (MLB), played between the American League and National League champions since 1903. The winner of the World Series championship is determined through a best-of-seven playoff and awarded the Commissioner's Trophy. As the series is played in October, Major League Baseball also refers to it as the "Fall Classic". The most recent World Series was won by the St. Louis Cardinals, who defeated the Texas Rangers in 7 games in 2011.

The New York Yankees of the American League have played in 40 World Series and won 27, and the Oakland/Philadelphia Athletics have played in 14 and won 9. In the National League, the St. Louis Cardinals have played in 18 and won 11, while the San Francisco/New York Giants and Los Angeles/Brooklyn Dodgers have both appeared in 18 and won 6.

Until the formation of the American Association in 1882 as a second major league, the National Association of Professional Base Ball Players (1871–75) and then the National League (founded 1876) represented the top level of organized baseball in the United States. All championships went to whoever had the best record at the end of the season, without a postseason series being played. Starting in 1884 and going through 1890, the National League and the American Association faced each other in a series of games at the end of the season to determine an overall champion. These matchups were disorganized in comparison to the modern Series: games played ranged from as few as three in 1884 (Providence defeated New York 3 games to zero), to a high of 15 in 1887 (Detroit beat St. Louis 10 games to 5), and both the 1885 and 1890 Series ended in ties, each team having won three games with one tie game.

World War I (WWI), which was predominantly called the World War or the Great War from its occurrence until 1939 (World War II), and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918. It involved all the world's great powers, which were assembled in two opposing alliances: the Allies (based on the Triple Entente of the United Kingdom, France and Russia) and the Central Powers (originally centred around the Triple Alliance of Germany, Austria-Hungary and Italy; but, as Austria–Hungary had taken the offensive against the agreement, Italy did not enter into the war). These alliances both reorganised (Italy fought for the Allies), and expanded as more nations entered the war. Ultimately more than 70 million military personnel, including 60 million Europeans, were mobilised in one of the largest wars in history. More than 9 million combatants were killed, largely because of enormous increases in lethality of weapons, thanks to new technology, without corresponding improvements in protection or mobility. It was the sixth-deadliest conflict in world history, subsequently paving the way for various political changes such as revolutions in the nations involved.