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 Domhnall I, Earl of Mar and his wife Helen. Almost the first blow in the war between Scotland and England was a direct attack on the Bruces. On 26 March 1296, Easter Monday, seven Scottish earls made a surprise attack on the walled city of Carlisle, which was not so much an attack against England as the Comyn Earl of Buchan and their faction attacking their Bruce enemies. Both his father and grandfather were at one time Governors of the Castle, and following the loss of Annandale to Comyn in 1295, it was their principal residence. Robert Bruce would have