The American Revolution opened new perspectives to unfettered trade, though for the moment primarily on the smuggling route via the WIC colony of Sint Eustatius. That entrepôt soon became an important export port for the supply of the American rebels with Dutch arms. The Amsterdam were particularly interested in opening formal trade negotiations with the Continental Congress; secret diplomacy was soon embarked upon by the pensionaries of a number of mercantile cities, like Engelbert François van Berckel (Amsterdam) and Cornelis de Gijselaar (Dordrecht), behind the back of the stadtholder and the States-General. The French ambassador to the Republic, Vauguyon, arranged contacts with the American ambassador to the French court, Benjamin Franklin, in 1778, which in time led to the sending out of John Adams as American emissary to the Republic. In 1778, there also were secret negotiations between the Amsterdam banker Jean de Neufville and the American agent in Aachen, William Lee. The two concluded a secret agreement on a treaty of amity and commerce between the two Republics, the draft of which was discovered by the British when they intercepted ambassador-to-the-Netherlands-to-be Henry Laurens at sea. They used this as a casus belli for declaring the Fourth Anglo-Dutch War in December 1780 (together with the actions from Dutch territory by the American privateer John Paul Jones, and the planned Dutch accession to the First League of Armed Neutrality). The war went disastrously for the Dutch, despite the fact that the Dutch fleet had been enlarged appreciably in the preceding years. but it was scarcely used by the Dutch, with the stadtholder, as Admiral-General, in supreme command. At the start of the war, a number of Dutch warships were surprised by ships of the Royal Navy, who according to the Dutch, sneaked up under a false flag, and when they had approached the unsuspecting Dutchmen (who were not yet aware of the start of the war), ran up their true colors and opened fire. The Dutch ships then struck their colors after firing a single broadside in reply "to satisfy honor." In this way individual ships, and even a complete squadron, were lost. The British blockaded the Dutch coast without much response from the Dutch fleet. There was one big battle between a Dutch squadron under rear-admiral Johan Zoutman and a British one under vice-admiral Sir Hyde Parker, which ended inconclusively, but on the whole the Dutch fleet remained in port,