During the negotiations in 1666 with Münster in the Second Anglo-Dutch War, Wilhelm found himself opposed by the Elector of Brandenburg. In 1670, while attempting to get Brandenburg to join the French alliance in the Franco-Dutch War, Wilhelm also asked the elector about his opinion of a successor for Leopold I, who was sick at the time. Wilhelm suggested again Louis XIV as the next Emperor, but Brandenburg preferred the Duke of Neuburg. When Wilhelm went to leave, he was delayed by the disappearance of some of his baggage, which included his money and diplomatic papers. The bags turned up the next day without the money, so Wilhelm considered it simple theft. He did not notice that his papers had been searched, and that the document detailing his discussions and plans for the Emperor's replacement was missing. This document would show up again as evidence of his treason against the Emperor at his trial. In 1671, the Elector of Brandenburg spoke many times to Leopold against the influence that Wilhelm was wielding on behalf of France, and the Emperor became more strongly opposed to Wilhelm's work.