The scientific operations were directed by Vauban, the first of living engineers.

That nothing might be wanting which could kindle emulation through all the ranks of a gallant and loyal army, the magnificent King himself had set out from Versailles for the camp.

Yet William had still some faint hope that it might be possible to raise the siege.

He flew to the Hague, put all the forces of the States General in motion, and sent pressing messages to the German Princes.

Within three weeks after he had received the first hint of the danger, he was in the neighbourhood of the besieged city, at the head of near fifty thousand troops of different nations.