By 1308 however, he had returned to his native Scotland to aid the cause of Robert the Bruce along with his brother Sir Edward of Sinton. Sir Robert commanded the Scots cavalry at Bannockburn in 1314.
In the Perth parliament of 1320, King of Scots Robert the Bruce rewarded Keith with a substantial grant consisting of the forest of Kintore and lands in Buchan along with the title “Great” Marischal. The estates of the Keiths were further extended during the 14th century to include the Dunnottar estate, south of Aberdeen as well as lants in Caithness and near Peterhead.
The Earldom of Marischal was created in 1458 for William Keith (c.1425-1483) following his role as one of the guarantors of the 1457 truce with England. This elevation secured the Keith’s status as loyal supporters of the Scottish crown and derived from their hereditary office, rather than from the granting of any Royal estates.