Abner Doubleday is better known for something he never did, than for what he did, which was important.
As an officer in the Union army, Abner Doubleday (1819-1893) commanded the firing of the North's first shots in defense of Fort Sumter, S.C., the opening battle of the American Civil War in 1861. This war has had an enormous enduring effect on the history and cultural mores of the United States, and the firing on Fort Sumter is one of its most famous episodes.
The lore of baseball makes Doubleday the inventor of the game, in a cow pasture in Cooperstown, New York, in 1839. This is false; baseball evolved slowly from an English game called Rounders. It has no single inventor. Recent scholarship casts doubt that Doubleday even codified the rules of the game.
A West Point graduate, before the civil war Doubleday served in the Mexican War and fought the Seminole Native Americans. By 1862 he was a Major-General, and was temporarily in command at the Battle of Gettysburg, before being relieved by General Howard.
At his death, Doubleday left a considerable supply of letters and papers, none of which describe baseball, or give any suggestion that Abner Doubleday considered himself a prominent person in the evolution of the game.