Dumbarton (dəmbärˈtən) [key], town (1991 pop. 23,550), West Dunbartonshire, W Scotland, at the confluence of the Leven and Clyde rivers. It is a shipbuilding center (the Cutty Sark was fitted out there) and has engineering works. Whisky (distilling and blending) is a major industry. Historical Scottish castles were built on Dumbarton Rock, a 250-ft-high (76-m) hill of basalt, from at least the 5th cent., when Dumbarton was the capital of the kingdom of Strathclyde. It became the capital of the earldom of Lennox in the 12th cent. and was granted a royal charter in 1222. Sir John de Monteith, the governor of Dumbarton Castle, betrayed William Wallace in 1305. As a result, Wallace was imprisoned in the castle.