The 1943 World Series matched the defending champion St. Louis Cardinals against the New York Yankees, in a rematch of the 1942 Series. The Yankees won the Series in five games for their tenth championship in 21 seasons. It was Yankees' manager Joe McCarthy's final Series win. This series was also the first to have a 'World Series highlight film' made for it (initially, the films were created as gifts to troops fighting in World War II, to give them a brief recap of baseball action back home), a tradition which continues to this day.

This Series was scheduled for a 3–4 format due to wartime travel restrictions. The 3–4 format meant there was only one trip between ballparks, but if the Series had ended in a four-game sweep, there would have been three games played in one park and only one in the other.

Due to World War II, both teams' rosters were depleted. Johnny Beazley, Jimmy Brown, Creepy Crespi, Terry Moore, and Enos Slaughter were no longer on the Cardinal roster. Joe DiMaggio, Phil Rizzuto, Red Ruffing, and Buddy Hassett were no longer on the Yankee roster. Also Yankee Red Rolfe retired to coach at Dartmouth College.

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.

Walter Brennan (July 25, 1894 – September 21, 1974) was an American actor. Brennan won the Academy Award for Best Supporting Actor on three separate occasions, which is currently the record for most Oscar wins by a male actor, tied with Jack Nicholson.

Born in Lynn, Massachusetts, less than two miles from his family's home in Swampscott, Walter Andrew Brennan was the second of three children born to Irish immigrants William John Brennan and Margaret Elizabeth Flanagan. The elder Brennan was an engineer and inventor, and young Walter studied engineering at Rindge Technical High School in Cambridge, Massachusetts.

While in school, Brennan became interested in acting, and began to perform in vaudeville. While working as a bank clerk, he enlisted in the U.S. Army and served as a private with the 101st Field Artillery Regiment in France during World War I. Following the war, he moved to Guatemala and raised pineapples, before settling in Los Angeles. During the 1920s, he became involved in the real estate market, where he made a fortune. Unfortunately, he lost most of his money when the market took a sudden downturn due to the Great Depression.^{[citation needed]}