is a real-time computer wargame designed by Sid Meier, the co-founder of Firaxis Games, then released in December 1999.

The game allows the player to control either the Confederate or Union troops during the Battle of Antietam of the American Civil War.

The staff of Computer Gaming World summarized it as "a grand experiment by Firaxis to test the popularity of online-only distribution for commercial releases.

The staff wrote, "Another battle, another victory for this thoroughly entertaining wargame 'for the masses.

They wrote, "Antietam is the epitome of a Sid Meier design: intensely absorbing and wickedly punishing.