Kingswear Castle was built between 1491 - 1502, as an artillery tower for use with heavy cannon. Due to the limited range of cannon at the time, the fort at Kingswear was designed to work alongside Dartmouth Castle on the opposite bank, so that between them they could provide complete cover of the narrow entrance into the harbour. As gun technology improved and the range of the weapons increased, new gun emplacements were added to Dartmouth Castle, aiming further out towards the estuary mouth, leading to a decline in the defensive role of Kingswear Castle.