Terrible Swift Sword: The Three Days of Gettysburg (often abbreviated as TSS) is a classic grand tactical, regimental level board wargame depicting the Battle of Gettysburg of the American Civil War. It was published by Simulations Publications, Inc. (SPI) in 1976, and remains one of the largest board wargames ever produced. TSS won the 1976 Charles S. Roberts Award for Best Tactical Game. It was considered groundbreaking among wargaming hobbyists.