The collapse of the 9th Army

General André Corap's 9th Army holds the Meuse sector between Sedan and Dinant — precisely where the German bridgeheads (Guderian, Reinhardt, Rommel) have just been established. Made up in part of second-rate reserve units, stretched across a wide front believed to be little threatened, it is struck head-on by the breakthrough.

Under the combined blows of the armour and the Luftwaffe, the front falls apart. Corap must react quickly. Attempt a general counter-attack to reduce the bridgeheads before they merge. Order a general withdrawal to reconstitute a line further back. Or hold in place, plugging the breaches one by one.

Time is working against him: with every hour, the Panzers widen the breaches and drive deeper. A decision that is too slow or poorly executed would turn the local rupture into the rout of an entire army, opening the road to the Channel. Corap has few mobile reserves and only fragmentary information about the true scale of the breakthrough.