70-pounder Whitworth naval gun

The 70-pounder Whitworth naval gun was designed by Joseph Whitworth during the 1860s. It was a rifled muzzle loader and used his hexagonal rifled bore design.

Service
Four guns were captured by the United States Navy on the blockade-runner Princess Royal on 29 January 1863. Two were sent to Morris Island, Charleston, South Carolina to bombard Fort Sumter during the summer of 1863. One gun had a premature detonation that killed four of its crew when trying to ram a projectile home. Another gun was disabled after 111 shots when its inner tube moved back far enough to block the vent.

A number of 70-pounders were bought by the Brazilian Navy and used to arm some of its ironclads during the Paraguayan War in the late 1860s.