A year after his defeat at the
Battle of Fleurus, Christian of Brunswick found himself in command of an
army of 15,000, freshly recruited and rested from winter quarters in the
United Provinces. He reopened his campaign in the summer of 1623 by marching into the
Lower Saxon Circle. With no support forthcoming from other Protestant princes, or even from Christian's recent ally
Ernst von Mansfeld, Christian now found himself in a precarious military position with little possibility of reinforcement. To add to this, Tilly had received word of Christian's movements and was now moving to confront him. The second half of July 1623 thus became a period of retreat for Christian's forces, as Tilly's troops had marched across the
Saxon border on 13 July. Christian reportedly marched across the
Weser River on 27 July and the
Ems River a few days later, with the Count of Tilly's more disciplined troops steadily gaining ground. When Christian left
Greven, (north of
Münster), on 4 August, Tilly was only half an hour behind. Christian's rearguard managed to ward off an engagement for two more days, holding the bridges first over the
Vechte (at
Metelen) and then over the
Dinkel (at
Heek). Tilly's army continued to pursue Christian's. His vanguard, commanded by
Johann Jakob, Count of Bronckhorst and Anholt, engaged Christian's rearguard, commanded by
Colonel Styrum, near Heek on the morning of 6 August, forcing Christian to fall back across the
Ahauser Aa (upper
Schipbeek), meeting up with the rearguard, commanded by
Baron Knyphausen, between the villages of Wessum and Wüllen. ==Battle==