Marlborough's march started on 19 May from Bedburg, northwest of Cologne. The army assembled by Marlborough's brother, General Charles Churchill consisted of 66 squadrons of cavalry, 31 battalions of infantry and 38 guns and mortars, totalling 21,000 men; 16,000 of whom were English. This force was augmented en route and by the time it reached the Danube, it numbered 40,00047 battalions and 88 squadrons. While Marlborough led this army south, the Dutch General Henry Overkirk, Count of Nassau maintained a defensive position in the Dutch Republic against the possibility of Villeroi mounting an attack. Marlborough had assured the Dutch that if the French were to launch an offensive he would return in good time, but he calculated that as he marched south, the French army would be drawn after him. In this assumption Marlborough proved correct: Villeroi shadowed Marlborough with 30,000 men in 60 squadrons and 42 battalions. Marlborough wrote to Godolphin "I am very sensible that I take a great deal upon me, but should I act otherwise, the Empire would be undone ..."