While the Allies were making their preparations, the French were striving to maintain and re-supply Marsin. He had been operating with Maximilian II against Prince Louis, and was somewhat isolated from France: his only lines of communication lay through the rocky passes of the Black Forest. On 14 May, Tallard brought 8,000 reinforcements and vast supplies and munitions through the difficult terrain, whilst outmanoeuvring , the Imperial general who sought to block his path. Tallard then returned with his own force to the Rhine, once again side-stepping Thüngen's efforts to intercept him.