A letter drawn up by the Duc de Sully was sent to Archduke Albert by the King.
"My brother," he said; "Not being able to refuse my best allies and confederates the help which they have asked of me against those who wish to trouble them in the succession to the duchies and counties of Cleve, Julich, Mark, Berg, Ravensberg, and Ravenstein, I am advancing towards them with my army.

As my road leads me through your country, I desire to notify you thereof, and to know whether or not I am to enter as a friend or enemy." Such was the draft as delivered to the Secretary of State; "and as such it was sent," said Sully, "unless Villeroy changed it, as he had a great desire to do." Henry was mistaken in supposing that the Archduke would leave the letter without an answer.

A reply was sent in due time, and the permission demanded was not refused.

For although France was now full of military movement, and the regiments everywhere were hurrying hourly to the places of rendezvous, though the great storm at last was ready to burst, the Archdukes made no preparations for resistance, and lapped themselves in fatal security that nothing was intended but an empty demonstration.
Six thousand Swiss newly levied, with 20,000 French infantry and 6000 horse, were waiting for Henry to place himself at their head at Mezieres.
Twelve thousand foot and 2000 cavalry, including the French and English contingents--a splendid army, led by Prince Maurice--were ready to march from Holland to Dusseldorf.

The army of the princes under Prince Christian of Anhalt numbered 10,000 men.