Sister of Robert the Bruce
Mary Bruce was the younger sister of Robert the Bruce, King of Scots. During the First War of Scottish Independence, she was captured by the English and imprisoned in a cage at Roxburgh Castle for about four years. She was the daughter of Robert de Brus, 6th Lord of Annandale, and Marjorie, Countess of Carrick. Along with the king's other female relatives, she was captured and betrayed to the English by the Earl of Ross.