But it was almost impossible to enforce such a system. It was foiled by the rise of a widespread contraband trade, by the reluctance of Holland to aid in its own ruin, by the connivance of officials along the Prussian and Russian shores, and by the pressure of facts. It was impossible even for Napoleon himself to do without the goods he pretended to exclude; an immense system of licences soon neutralized his decree; and the French army which marched to Eylau was clad in greatcoats made at Leeds, and shod with shoes made at Northampton. Vexatious therefore as the system might be at once to England and to Europe, it told on British industry mainly by heightening the price of its products, and so far by restricting the market for them. But it told far more fatally on British commerce. Trade at once began to move from English vessels, which were subject to instant confiscation, and to shelter itself under neutral flags, where goods had at least to be proved to be British before they could be seized. America profited most by this transfer. She was now entering on that commercial career which was to make her England's chief trading rival; and she rapidly availed herself of the Berlin decree to widen her carrying trade. But the British Government at once felt the pressure of the merchant class. As yet this class had profited above all others by the war and by the monopoly which war placed in its hands; and now that not only its monopoly but its very existence was threatened, it called on the Government to protect it. It was to this appeal that the administration of Lord Grenville replied, in January 1807, by an Order in Council which declared all the ports of the coast of France and her allies under blockade, and any neutral vessels trading between them to be good prize. [Sidenote: Fall of the Grenville Ministry.]