Although during his lifetime Doubleday was noted for his military accomplishments, the historical significance attributed to him has been based primarily on his supposed invention of the game of baseball. In 1905 a commission was established to determine whether baseball had uniquely American origins or was descended from rounders, a game of English origin….The de facto leader of the commission was Abraham G. Mills, a former president of the National League, who in this capacity spent two years collecting written anecdotal recollections from interested persons nationwide on the matter, but he acquired little substantive evidence to support either claim. One such anecdote that piqued Mills's interest was provided by Cooperstown resident Abner Graves, who testified that he and Doubleday were schoolmates and that in 1839 Doubleday redesigned a game played by local residents known as "town ball." Doubleday, he said, instituted a smaller number of participants and a new set of rules and renamed the game "base ball." Doubleday may have played a game similar to that of baseball as a child or teenager in Cooperstown, but his status in 1839 as a second-year cadet at West Point makes a prolonged appearance in Cooperstown at that time unlikely. Moreover, no record has been found, even in Doubleday's many writings, that he ever played baseball.
Brooks D. Simpson and Matthew E. Van Atta, "Doubleday, Abner," American National Biography Online, February 2000, http://www.anb.org/articles/05/05-00198.html.