The French engineers at Sedan

At Sedan, the defence rested on the line of the Meuse: as long as the river was not crossed, the German breakthrough was contained. The French engineers were charged with preparing the destruction of the bridges and hindering any crossing, while the infantry and artillery held the south bank. But the sector was defended by mediocre reserve units, and coordination left much to be desired.

On 13 May, under the deluge of Stukas, the situation deteriorated. The engineers had to decide how to use their means. They could destroy all bridges and crossings without delay, even at the cost of isolating any friendly elements on the north bank. They could wait for clear orders, at the risk of being outpaced by an enemy already crossing in boats. Or they could concentrate their effort on mining and obstacles as close as possible to the probable crossing points.

Speed and coordination were vital: a successful crossing by the enemy, for want of effective demolitions and obstacles, would open the decisive breach. Yet the disorganisation, the nascent panic (Bulson) and German air supremacy compromised the engineers' action at the crucial moment.