The Treaty of Dover included an agreement by Charles II to supply a brigade of 6,000 English and Scottish troops for the French army. It also contained secret provisions, not revealed until 1771, one being the payment to Charles of £230,000 per year for these troops. While Charles was anxious to ensure Louis felt he was getting value for money, there were considerable doubts as to the brigade's reliability if asked to fight the Protestant Dutch on behalf of the Catholic French. As a result, it formed part of Turenne's force in the Rhineland but several officers, including the Duke of Monmouth and John Churchill, future Duke of Marlborough were present at Maastricht as volunteers and given prominent positions by Louis to gratify his English ally. The attacking forces numbered about forty thousand men.