They invaded on two fronts in June 1635, but soon the Spanish forces regained the initiative against the combined Franco-Dutch army, which was ignominiously driven to the Dutch border.

In the summer of 1636 the Cardinal-Infante reached as far as Corbie during the Crossing of the Somme, but this city was retaken by the French in November, and at the end of the year Spain had lost most of its gains.

[3] Breda was the capital city of the baronial fief that had once been the crown jewel in the Dutch estates of the Nassau family in the Habsburg Netherlands before the war started.

[4] Frederick Henry set up his headquarters here and the besiegers started to dig a double line of circumvallation that would eventually reach a circumference of 34 km.

An outer contravallation (8 ft. deep and 16 ft. wide) defended the besiegers from outside interference, and outside this area the low-lying countryside was inundated by damming a few rivers.

[5] Unlike the strategy adopted by Ambrosio Spinola at Breda in 1624–25, Frederick Henry did not plan on a passive siege, aimed at starving the fortress, but intended a more aggressive approach.

[7] Undistracted, the besiegers meanwhile started digging covered trenches inward from the circumvallation line toward the hornworks of the fortress, which had been constructed by the Dutch themselves on the model of a star fort.

Frederick Henry made an attempt to capture Antwerp, but his advance guard was caught in the open by a crack Spanish force on 20 June 1638 and defeated in the only pitched battle of the second part of the Eighty Years' War at Kallo.