When additional French troops arrived in Leith, Edinburgh's seaport, the Protestants responded by retaking Edinburgh. This time, on 24 October 1559, the Scottish nobility formally deposed Mary of Guise from the regency. Her secretary, William Maitland of Lethington, defected to the Protestant side, bringing his administrative skills. From then on, Maitland took over the political tasks, freeing Knox for the role of religious leader. For the final stage of the revolution, Maitland appealed to Scottish patriotism to fight French domination. Following the Treaty of Berwick, support from England finally arrived and by the end of March, a significant English army joined the Scottish Protestant forces. The sudden death of Mary of Guise in Edinburgh Castle on 10 June 1560 paved the way for an end to hostilities, the signing of the Treaty of Edinburgh, and the withdrawal of French and English troops from Scotland. On 19 July, Knox held a National Thanksgiving Service at St Giles'.