James III was the son of James II and succeeded to the throne of Scotland in 1460 on his father's death. Once more Scotland had a child king -- born in 1451, James was only 9 when he succeeded. His mother, Mary of Gueldres, acted as Regent for him, until she died, but the kingdom was riven by jealousies between certain powerful families, most notably the Boyds who, after Mary's death, seized the king in 1466, and married their son, Thomas, to the king's sister, Mary. They also arranged for James to marry Princess Margaret, daughter of the king of Denmark (thereby gaining Orkney and Shetland as a guarantee for the dowry, which, never being paid, meant that the islands were finally joined to Scotland). James was to have 3 children with Margaret -- a son, named James, a second James who became Duke of Ross, and John, who succeeded to the Earldom of Mar.
King James was jealous of the power the Boyds had and, after his marriage in 1469, he set out to destroy them. Unfortunately two of the king's brothers, Alexander, Duke of Albany, and John, Earl of Mar, also sought the throne, and James was forced to resist them. Mar died, whilst in royal custody (leading other nobles to fear for their safety), and Albany escaped, fled to England, and allied with Edward IV (who purported to declare him King of Scotland), and tried an invasion in 1482, and when this failed, was obliged to flee to France.
The Scottish nobility took against their king -- they resented that he was unwilling to go to war with England and that he appeared happy that the English royal family were marrying their children to Scots families. They accused him of being spendthrift, and of having favourites and alleged that he was bisexual. At one point, led by the Douglas Earl of Angus, they executed all the court but the king, and imprisoned him for three months. On his release, and seeing no sign of a change in his habits, in 1488 the nobility declared war on their king, in favour of his son, James, then 15. The prince agreed to their support so long as his father was not hurt, but in the event, having been wounded in a fall from his horse, the king was assassinated by an unknown dagger-wielder.
This page was based on a variety of on-line sources.