[10] The States determined to open the campaign with the siege of Steenwijk, a strongly fortified town on the route from the IJssel at Deventer in order to cut off Groningen further.

The Duke of Parma had marched into France, leaving Ernst I von Mansfeld as his deputy, while Francisco Verdugo was in command of the area as the Spanish Stadtholder of Friesland, Groningen, Drenthe, and Overijssel.

[9] Steenwijk is located in the northern corner of the province of Overijssel, bordering on the Zuyder Zee, called Vollenhove.

Steenwijk was held largely by a militia garrison of sixteen companies of foot and some cavalry under Antonio Coquel who was the military governor.

[14] The effort however largely failed since only sixty managed to join the garrison having slipped past - most were killed or captured.

[5] Ten days later three mines had been run under the defences, besides a way through the ditch, from the English approaches under the Eastern bulwark and the Oeningerpoort.

[14] On the night of 3 July the whole army was secretly drawn into the trenches, and at dawn the mines were to be fired and a general assault delivered.

[3] The soldiers carried the ruined bastion only to find the Spanish had drawn back and opened fire on the Dutch killing and wounding many but they held what they had taken.

[11] The third explosion also made a great breach on the Gasthuys bulwark, but here upwards of 100 of the waiting Dutch troops ready to assail were buried alive.

Maurice's force had lost 600 men nearly half of these were inflicted in the failed third assault, and he was himself slightly wounded in the face.

[11][17] By conquering Steenwijk the Spaniards were cut off from the Zuiderzee, from which the Republic's ships could then sail through safer on the inland sea.

[5] With Steenwijk secure the Spanish pressure in the East was relaxed and Maurice conducted training with the troops at Giethoorn learning how to turn, advance, retreat, double their lines, and so on.