When Maurice arrived in front of the place on 1 July, he sent two thirds of his force across the Yser River to blockade it from the West. That night, while he was making preparations for a regular siege, he received news that the Archduke was close at hand with a field army; knowing that he was cut off from his base, he ordered his cousin Ernst Casimir (Ernst Casimir I of Nassau-Dietz) to delay with a force the advancing Spanish troops, while he was bringing the best part of his army to cross again the Yser and rejoin the rest, to face the Archduke: he had no option left but to present battle, or risk a potentially disastrous retreat by sea.