Until the night of August 15th there was little indication that anything big was afoot, and the first hint was an artillery barrage aimed at the 90th's troops in the vicinity of Le Bourg-Saint-Léonard. The next morning reports of extensive enemy activity in the Forêt de Gouffern came streaming in. Artillery liaison pilots reported great convoys of enemy vehicles and troops swarming throughout the valley.
Forward observers rubbed their eyes incredulously as they saw targets they had never dreamed could exist.
At noon the 16th the enemy attacked in force the 90th's road block at Le Bourg-Saint-Léonard in a desperate effort to clear the shoulders of their escape rout. All day the battle raged, with the town changing hands several times.
Tanks battled furiously throughout the encounter, tank destroyers waded into the fight with guns blazing, the doughboys stood fast, containing the frantic Seventh Army within its narrow bottleneck. And the artillery blasted away with everything it had.
That night the 90th was released from the XV Corps and passed to the control of a Provisional Corps whose function it was to reduce the Falaise pocket.
The mission of the 90th was to attack north, seize the village of Omméel and the high ground northeast of Chambois.
Since the main road by which the Seventh Army sought escape ran directly through Chambois, the control of that town was vital to the Americans, as well as to the enemy.