May 1544 the gunner Andrew Mansioun firing from the castle destroyed an English cannon placed to bombard the forework. In 1547 disaffected members of the garrison who resented Regent Arran came to Norham Castle and offered to let the English in. Refortification in 1548 included an earthen angle-bastion, known as the Spur, of the type known as trace italienne, one of the earliest examples in Britain. Brunstane Castle the home of the traitor Alexander Crichton was demolished to provide building materials. The Spur may have been designed by Migliorino Ubaldini, an Italian engineer from the court of Henry II of France, and was said to have the arms of France carved on it. James V's widow, Mary of Guise, acted as regent from 1554 until her death at the castle in 1560. The following year, the Catholic Mary, Queen of Scots, returned from France to begin her reign, which was marred by crises and quarrels amongst the powerful Protestant Scottish nobility. In 1565, the Queen made an unpopular marriage with Henry Stuart, Lord Darnley, and the following year, in a small room of the Palace at Edinburgh Castle, she gave birth to their son James, who would later be King of both Scotland and England. Mary's reign was, however, brought to an abrupt end. Three months after the murder of Darnley at Kirk o' Field in 1567, she married James Hepburn, 4th Earl of Bothwell, one of the chief murder suspects. A large proportion of the nobility rebelled, resulting ultimately in the imprisonment and forced abdication of Mary at Loch Leven Castle. She escaped and fled to England, but some of the nobility remained faithful to her cause. Edinburgh Castle was initially handed by its Captain, James Balfour, to the Regent Moray, who had forced Mary's abdication and now held power in the name of the infant King James VI. Shortly after the Battle of Langside, in May 1568, Moray appointed Sir William Kirkcaldy of Grange Keeper of the Castle. Grange was a trusted lieutenant of the Regent, but after Moray's murder in January 1570 his allegiance to the King's cause began to waver. Intermittent civil war continued between the supporters of the two monarchs, and in April 1571 Dumbarton Castle fell to "the King's men". Under the influence of William Maitland of Lethington, Mary's secretary, Grange changed sides, occupying the town and castle of Edinburgh for Queen Mary, and