Morton was elected to Mar's office and proved in many ways the most effective of James's regents, but he made enemies by his rapacity. He fell from favour when Frenchman Esmé Stewart, Sieur d'Aubigny, first cousin of James's father Lord Darnley and future Earl of Lennox, arrived in Scotland and quickly established himself as the first of James's powerful favourites. James was proclaimed an adult ruler in a ceremony of Entry to Edinburgh on 19 October 1579. Morton was executed on 2 June 1581, belatedly charged with complicity in Darnley's murder. On 8 August, James made Lennox the only duke in Scotland. The king, then fifteen years old, remained under the influence of Lennox for about one more year.