In addition to the RAF, the anti-aircraft defences were key to holding off the German air force at Dunkirk. Hence, the order was given to keep the anti-aircraft guns going to the last, with any spare gunners to join the infantry.
Shell case for a British 3.7" Anti-Aircraft round.
Tragically, as the order went down the chain of command, the meaning got twisted. Ultimately, the signal was interpreted by the commander of the anti-aircraft defences to mean that all gunners should make their way to the beach for evacuation. Given that the beachhead was under constant air attack, it seems amazing that the order was never questioned. It is alleged that the commander responsible presented himself to General Adam (Commander of the Dunkirk perimeter) in the early hours of the 28th May, saluted smartly and announced "All anti-aircraft guns have been spiked and gunners evacuated." Receiving this news, an incredulous General Adam is reputed to have paused, looked up and despatched the errant officer with the words, "You bloody fool, go away!"
Clip of 4 rounds for the 40mm Bofors Anti-Aircaft gun.