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 against the new regent, the Earl of Lennox. The stand-off which followed was not resolved until two years later, and became known as the "Lang Siege", from the Scots word for "long". Hostilities began in May, with a month-long siege of the town, and a second short siege in October. Blockades and skirmishing continued meanwhile, and Grange continued to refortify the castle. The King's party appealed to Elizabeth I of England for assistance, as they lacked the artillery and money required to reduce the castle, and feared that Grange would receive aid from France and the Duke of Alba in the Spanish Netherlands. Elizabeth sent ambassadors to negotiate, and in July 1572 a truce was agreed and the blockade lifted. The town was effectively surrendered to the King's party, with Grange confined to the castle.