While the assault was going on, the artillery of the besiegers continued to play upon other parts of the town, and effected great damage. On the following night the garrison endeavoured to capture the bridge across the Haven, but were repulsed with loss, and in the morning the place surrendered. The success of the patriots was due in no slight degree to the fact that Parma with the greatest part of his army was again absent in France, and the besieged towns had therefore no hope of assistance from without. The States now determined to seize the opportunity of capturing the towns held by the Spaniards in Friesland. The three principal towns in the possession of the Spaniards were Groningen, Steenwyk, and Coevorden. After capturing several less important places and forts Prince Maurice advanced against Steenwyk. But just as he was about to commence the siege he received pressing letters from the States to hurry south, as Parma was marching with his whole army to capture the fort of Knodsenburg, which had been raised in the previous autumn as a preparation for the siege of the important city of Nymegen. The Duke of Parma considered that he had ample time to reduce Knodsenburg before Prince Maurice could return to its assistance. Two great rivers barred the prince's return, and he would have to traverse the dangerous district called the Foul Meadow, and the great quagmire known as the Rouvenian Morass. But Prince Maurice had now an opportunity of showing the excellence of the army he had raised and trained. He received the news of Parma's advance on the 15th of July; two days later he was on the march south, and in five days had thrown bridges of boats across the two rivers, had crossed morass and swamp, and appeared in front of the Spanish army. One assault had already been delivered by the Spaniards against Knodsenburg, but this had been repulsed with heavy loss. As soon as the patriot army approached the neighbourhood, Parma's cavalry went out to drive in its skirmishers. Vere at once proposed to Prince Maurice to inflict a sharp blow upon the enemy, and with the approval of the prince marched with 1200 foot and 500 horse along the dyke which ran across the low country. Marching to a spot where a bridge crossed a narrow river he placed half his infantry in ambush there; the other half a quarter of a mile further back. Two hundred light cavalry were sent forward to beat up the enemy's outposts, and then retreat; the rest of the cavalry were posted in the rear of the infantry. Another dyke ran nearly parallel with the first, falling into it at some distance in the rear of Vere's position, and here Prince Maurice stationed himself with a body of horse and foot to cover Vere's retreat should he be obliged to fall back. About noon the light cavalry skirmished with the enemy and fell back, but were not followed. About half an hour later the scouts brought word that the Spaniards were at hand.