Neither in the letter to Beresford nor in that to Bathurst does Wellington make a forecast beyond the first stage of his advance--obviously it would be impossible to do so till it was seen how the French would act. If they should be tempted to fight--say in front of Valladolid--when their flank was turned, in order to keep their hold on Castile, Wellington would welcome the decisive engagement. But of course they might refuse to fight, as indeed did they. They retired on Burgos, as we shall see, without taking any risks. But that Wellington already foresaw the possibility of a victorious march to the Pyrenees is, I think, proved not only by his letter of February 10th concerning the siege of fortresses in Northern Spain, quoted above, but by similar hints on May 6 concerning the absolute necessity for naval co-operation in the North. He asks Lord Bathurst to insist on the presence of a squadron under an admiral in the Bay of Biscay, and for careful supervision of the whole coast from Bayonne to Corunna, which must absolutely stop French enterprise at sea, and ‘simplify arrangements for convoy and naval operations in concert with the army during the ensuing campaign[453].’ Taking this in conjunction with the letter of February 10, it seems certain that Wellington was thinking of stores to be landed at Santander, and a battering train to destroy San Sebastian--which was to look forward some way! There was, however, a secondary reason for requiring more naval supervision in the Bay of Biscay: American privateers had been putting in an appearance in these waters, and had captured several small transports.