Turenne had to fight every foot of his way in order to dislodge the enemy, and it was not until Enghien had brought the battle to a conclusion on his side, that Turenne arrived and, forcing the intrenchments guarding the mouth of the defile, found himself in contact with Merci, who was now able to concentrate his whole force against him.

The combat was a furious one.

The troops were engaged at but forty paces apart, and sometimes had hand-to-hand encounters.
Merci brought the whole of his cavalry into play, but Turenne was unable to use his, as they were behind his infantry and could not make their way out through the mouth of the defile.
For seven hours the battle raged in the darkness.

After losing three thousand men here, General Merci decided that his army would be totally destroyed if Enghien should bring his troops down from the hill at daybreak.

Accordingly, leaving a body of musketeers to hide the movement by their fire, he withdrew the rest of his army and took up another strong position, partly on a height known as the Black Mountain, covering the entrance of the valley of St.Pierre and partly in the valley itself, thus covering his line of retreat.