USS Alert was a 90 long tons (91 t) steamship named A. C. Powell purchased by the Union Navy during the first year of the American Civil War. A. C. Powell – later renamed Alert, and still later renamed Watch – served primarily as a tugboat, but at times she performed duty as a dispatch boat, ship's tender, and even as a gunboat despite the fact that she had on board only a howitzer instead of a cannon or rifle.