Just over a month later, the German Army launched its long-awaited offensive on the Western Front. The battalion moved to the Belgian border and to Courtrai. Under constant German bombardment, Whistler had sent a famous message to Brigade Headquarters "Please may I have half a Hurricane for half an hour". As the Germans advanced during the Battle of France, the battalion took up a defensive position at Caestre. An officer reported finding Whistler "standing in the middle of the street with a positive hail of explosives coming down all around". While his subordinates crouched by the side of the road, he "stood there with his hands in his pockets, laughing at us". Although attacked by tanks, planes and heavy artillery, the stand at Caestre was so strong that the Germans decided to by-pass this pocket of resistance. Whistler was awarded the Distinguished Service Order (DSO) for his leadership of the battalion in France. Orders were issued to withdraw to Dunkirk and most of the battalion evacuated to England on 30 May. Whistler became known as "The Man who went Back to Dunkirk". Although secrecy surrounds this operation, however, Whistler's adjutant, then-Captain J. B. Ashworth (later to succeed him as Colonel of the Royal Sussex Regiment), was convinced he returned to look for any missing men, and the records show that he came back separately to the United Kingdom with the 5th Battalion of the Manchester Regiment, part of the 127th Brigade of Major General William Holmes's 42nd (East Lancashire) Infantry Division, on 1 June. Ironically, the 127th Brigade was, at that time, commanded by Brigadier John Smyth, who was later to write Whistler's biography.