During the Marian Civil War the castle was held by William Kirkcaldy of Grange for Mary, Queen of Scots. He modified and strengthened the spur. Workers were reinforcing the spur in April 1571 with earth in baskets called "gabions" when a man fell to his death. The spur was described by Rowland Johnson, Surveyor of Berwick who came to assist the siege of Edinburgh Castle on 26 January 1573 during civil war in Scotland;"we fynd upon the said este syde a spurre lyke a bulwarke standing befor the foot of the rocke, which spurre enclosethe that syde flanked out one bothe sydes; on the sowthe syde is the gaite wher they enter the castle. Which spur is like 20 foote high vamured with turf and basketes set and furnished with ordinance."