William Sinclair was created Earl of Caithness in 1455 by King James II of Scots (1437-1460). By 1470 William reluctantly resigned his title Earl of Orkney with his encompassing Island estates, including his castle of Kirkwall to King James III of Scots (1460-1488) in exchange for the incomplete castle of Ravenscraig on the Fifeshire coast and other token lands. The resigned Orkney estate was then used as a dowry for the King's marriage to Princess Margaret of Denmark. In effect Orkney became a Stewart interest much to the dismay of the disinherited Sinclairs, who continued to interfere in the Orkney estates. Notably in 1529 at the battle of Summerdale north of Kirkwall when George 3rd Earl of Caithness was slain along with all of his men while fighting his own distant kin the Sinclairs of Orkney on behalf of King James V of Scots (1513-1542) and again during the reign of King James VI of Scots (1567-1603) when George 5th Earl of Caithness sent another Sinclair army which successfully routed the Stewart rebels led by Patrick Stewart Earl of Orkney.
