 He returned to Edinburgh, on the way writing a letter in French to his wife from Falahill mentioning he had three days of illness.The next month his army suffered a serious defeat at the Battle of Solway Moss.He took ill shortly after this, on 6 December; by some accounts this was a nervous collapse caused by the defeat, and he may have died from the grief, although some historians consider that it may just have been an ordinary fever.