Baseball and the Civil War have long been linked – erroneously – thanks to the myth of Abner Doubleday’s “invention”, but it has a tie far more interesting than the fictional one:

One hundred forty-nine years ago, two teams made up of members of the Union Army faced off against each other in a Christmas Day baseball game in Hilton Head, South Carolina. The Civil War is widely credited as having been a factor in spreading baseball across the country, and historical records exist for a number of the games played during the war — Baseball Almanac notes at least five in 1862 alone. The Christmas Day game was probably the best-attended game of the war, perhaps one of the best-attended games of the 19th century. But we don’t know that for certain, or indeed much of anything about the game, not even its final score.

One reason for the confusion is the unreliable source at the heart of the story. The game’s most famous player was A.G. Mills, the namesake of the Mills Commission, which established Abner Doubleday as the “founder” of baseball and Cooperstown as its birthplace on the basis of virtually no evidence. Mills played in the game when he was an 18-year old private with the New York Volunteers…

http://www.fangraphs.com/blogs/index.php/the-civil-warchristmas-day-game-hilton-head-1862/