For a more detailed description of the James III see the Article about James III in Wikipedia.
King James III (May 1452-June 11, 1488) was the first Scottish monarch of Shetland between 1472-1488. Despite his numeral, he would in fact be the first James to have ruled Shetland. Orkney and Shetland were annexed by him, for the nonpayment of the dowry of Margaret of Denmark, his wife.
After his death at the Battle of Sauchieburn, near Stirling, the throne fell to his son, the 15 year old James IV.