He took up a military career as a young man, but was also considered by other Scottish barons to be something of a leader, being appointed justiciary of the lands beyond the River Forth.

The battle was a decisive victory for the Scots, following which Bruce had undisputed military control of Scotland, excepting the Royal Burgh of Berwick-upon-Tweed.

He was killed fighting for King David II of Scotland at the Battle of Dupplin Moor.

Keith's indirect descendants, eventually known as the Earls Marischal, held that title for several centuries to come.

During the English Civil War, one of his descendants fought as a Royalist officer, and was imprisoned under Oliver Cromwell's regime.