Robert the Bruce's grandfather was one of the claimants to the throne of Scotland on the death of Queen Margaret, Maid of Norway, in 1290. While he was unsuccessful, his grandson refused support for John Balliol who had been selected by the English King Edward I. Robert the Bruce lent support to William Wallace and became a Guardian of Scotland, but when Edward offered a truce in 1302, Robert accepted and joined Edward's "Scottish Council". On the death of his father, Robert was reputedly the richest man in England.

In 1306 Robert declared himself King of Scotland. and he began a guerilla war against the English King Edward I. Gradually, with increasing support, he captured a number of castles, allowing the defenders to return to England. He sent the "Declaration of Arbroath" to the Pope in Rome, pleading the case for a Scotland's independence. He defeated the English army at the Battle of Bannockburn in 1314 and defeated Edward II's invasion in 1322 with a "scorched earth" policy. Edward III of England eventually agreed to the Treaty of Edinburgh in 1328 which recognized Scotland's independence and ending 30 years of war.

King Robert was gravely ill by this time and died at Cardross on 7 July 1329. His body was buried in Dunfermline Abbey. At his request, his heart was taken on a Crusade by James Douglas. In a fight against the Moors in Spain, Douglas was killed and the embalmed heart was returned to Scotland. It was buried in Melrose Abbey, and the stone marker is inscribed (in Scots) with "A noble hart may hae nae ease, gif freedom failye" (Eng. "A noble heart may have no ease if freedom fails").