In his role on committees overseeing the military he directed the provisioning of supplies for Cromwell's conquest of Ireland. As a leading member of the committee overseeing the navy (where he was joined by schoolmate Thomas Scot), he directed affairs in the naval First Anglo-Dutch War (1652–1654). After the navy's disastrous performance against the Dutch in 1652, Vane headed the committee that reformed the navy, drafting new Articles of War and formally codifying naval law. Vane's reforms were instrumental in the navy's successes later in the war. He was also involved in foreign diplomacy, going on a mission to France (whose purpose is unknown) in 1652 to meet with Cardinal de Retz, and travelling again to Scotland to organise the government there after Cromwell's victories in the Third English Civil War.