In this siege, for the first time, the spade was used by soldiers in the field. Hitherto the work had been considered derogatory to troops, and peasants and miners had been engaged for the work; but Prince Maurice had taught his soldiers that their duty was to work as well as fight, and they now proved the value of his teaching. The besieged made several successful sorties, and Sir Francis Vere had been severely wounded in the leg. The cannonade effected but little damage on the strong walls; but the soldiers, working night and day, drove mines under two of the principal bastions, and constructed two great chambers there; these were charged, one with five thousand pounds of powder, the other with half that quantity. On the 3d of July the mines were sprung. The bastion of the east gate was blown to pieces and the other bastion greatly injured, but many of the Dutch troops standing ready for the assault were also killed by the explosion. The storming parties, however, rushed forward, and the two bastions were captured. This left the town at the mercy of the besiegers. The next day the garrison surrendered, and were permitted to march away. Three hundred and fifty had been killed, among them young Count Lewis Van der Berg, and two hundred had been left behind, severely wounded, in the town. Between five and six hundred of the besiegers were killed during the course of the siege. The very day after the surrender of Steenwyk Maurice marched away and laid siege to Coevorden. This city, which was most strongly fortified, lay between two great swamps, between which there was a passage of about half a mile in width. Another of the Van der Bergs, Count Frederick, commanded the garrison of a thousand veterans. Verdugo sent to Parma and Mondragon for aid, but none could be sent to him, and the prince worked at his fortifications undisturbed. His force was weakened by the withdrawal of Sir Francis Vere with three of the English regiments, Elizabeth having sent peremptory orders that this force should follow those already withdrawn to aid Henry of Navarre in Brittany. Very unwillingly Vere obeyed, and marched to Doesburg on the Yssel. But a fortnight after he arrived there, while he was waiting for ships to transport him to Brittany the news came to him that Verdugo, having gathered a large force together, was about to attack Prince Maurice in his camp, and Vere at once started to the prince's aid.