Clan Sinclair to St Briavels Castle, and in 1296 he swore fealty to Edward I of England. In 1303 the Battle of Roslin took place where Scots under Henry Sinclair of Rosslyn and the Clan Comyn defeated an English force. The Battle of Loudoun Hill took place in 1307 where Scots under Robert the Bruce, assisted by Henry Sinclair of Rosslyn again defeated the English. The family initially favoured John Balliol's claim to the throne but later it became paramount that they gave their loyalty to Robert the Bruce. The Battle of Bannockburn was fought in 1314, where the Clan Sinclair fought
Robert the Bruce eventually lifted Bruce's excommunication. In May 1328 King Edward III of England signed the Treaty of Edinburgh-Northampton, which recognised Scotland as an independent kingdom, and Bruce as its king. In 1325 Robert I exchanged lands at Cardross for those of Old Montrose in Angus with Sir David Graham. It was to be here that Robert would build the manor house that would serve as his favoured residence during the final years of his reign. The extant chamberlain's accounts for 1328 detail a manor house at Cardross with king's and queen's chambers and glazed windows, a chapel, kitchens, bake- and brew-houses,