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In page Threave Castle:

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In 1452 the Earl seized Patrick Maclellan of Bombie, Sheriff of Galloway, and imprisoned him at Threave. Despite the King requesting his release, Maclellan was murdered. On 22 February 1452, Douglas was summoned to Stirling Castle, under a safe conduct by the King, who requested his aid against the rebellious Earls of Crawford and Ross. However, Douglas had signed a bond with these earls and refused to support the King, who responded by stabbing Douglas. He was then attacked and killed by the King's retainers, and his body thrown from a window.