One error brought the scheme to ruin, an error neither of strategy nor of conduct, but of scientific knowledge. John had miscalculated the time at which, on that night, the Seine would be navigable upstream, and his counsellors evidently shared his mistake till it was brought home to them by experience. The land forces achieved their march without hinderance, and at the appointed hour, shortly before daybreak, fell upon the French camp with such a sudden and furious onslaught that the whole of its occupants fled across the pontoon, which broke under their weight. But the fleet, which had been intended to arrive at the same time, was unable to make way against the tide, and before it could reach its destination the French had rallied on the northern bank, repaired the pontoon, recrossed it in full force, and routed John's troops. The ships, when they at last came up, thus found themselves unsupported in their turn, and though they made a gallant fight they were beaten back with heavy loss. In the flush of victory one young Frenchman contrived to set fire to the island fort; it surrendered, and the whole population of the New Andely fled in a panic to Château Gaillard, leaving their town to be occupied by Philip. The Saucy Castle itself still remained to be won. Knowing, however, that for this nothing was likely to avail but a blockade, which was now practically formed on two sides by his occupation of the island fort and the Lesser Andely, Philip on the very next day set off to make another attempt on Radepont, whence he had been driven away by John a year before. This time John made no effort to dislodge him. It was not worth while; the one thing that mattered now was Château Gaillard. Thither Philip, after receiving the surrender of Radepont, returned toward the end of September, 1203, to complete the blockade. No second attempt to relieve it was possible. It may have been for the purpose of endeavoring to collect fresh troops from the western districts, which were as yet untouched by the war, that John about this time visited his old county of Mortain, and even went as far as Dol, which his soldiers had taken in the previous year. But his military resources in Normandy were exhausted; the Marshal bluntly advised him to give up the struggle. "Sire," said William, "you have not enough friends; if you provoke your enemies to fight, you will diminish your own force; and when a man provokes his enemies, it is but just if they make him rue it." "Whoso is afraid, let him flee!" answered John. "I myself will not flee for a year; and if indeed it came to fleeing, I should not think of saving myself otherwise than you would, wheresoever you might be." "I know that well, sire," replied William; "but you, who are wise and mighty and of high lineage, and whose work it is to govern us all, have not been careful to avoid irritating people. If you had, it would have been better for us all. Methinks I speak not without reason."