Towards the end of May 1940, the Allies found themselves nearly trapped in the Low Countries. The Germans executed a swift advance, which inadvertently left their flanks vulnerable to a counterattack. Seizing the opportunity, the British promptly launched an offensive with 86 tanks. The mighty advance was split into two columns, positioned approximately five kilometers apart, while an additional 60 French tanks bolstered the main force. On the opposite side was General Erwin Rommel and his exceptional 7th Panzer Division. The Allied attack was successful at first. Numerous Germans were taken prisoner, and the British tanks demonstrated immunity to their 3.7-centimeter PaK guns. Overcome with panic, the Germans realized their weapons were ineffective against the enemy armor, prompting General Rommel to muster all available artillery, including a potent weapon: the 8.8-centimeter Flak. The combined firepower ultimately halted the British advance and forced them into a retreat. But notably, the most lethal German weapon of World War 2 was not originally intended to be an anti-tank gun at all.