The 4DCr launched an attack on 17 May at the Battle of Montcornet, where it successfully threw back the German defenses but had to retreat on its starting positions for lack of support and air cover. It then moved south of Abbeville to attack German bridgeheads across the Aisne river, fighting the Battle of Abbeville on 28/29 May with the aim of breaking through to the encircled Allied units trapped in Dunkirk.