In April, the 13th Brigade was involved in the counterattack at Villers-Bretonneux. On 21 April, in the lead up to the battle, the German fighter pilot, Manfred von Richthofen (the "Red Baron") was shot down over Australian lines, north of Villers-Bretonneux at Corbie. There are many theories as to who shot him down, one of which is that an Australian Vickers machine gunner, Sergeant Cedric Popkin of the 24th Machine-Gun Company, 4th Division, fired the actual bullet that killed von Richthofen. At dawn on 24 April, the Germans launched their attack, supported by armoured vehicles and a heavy artillery bombardment, that included mustard gas. With the situation urgent, the British III Corps ordered a counter-attack from the Australian 13th and 15th Brigades to retake the town. The attack was launched around 10 pm that night, with the two brigades isolated the town, enveloping it from the north and south, before entering it on Anzac Day to begin mopping up operations, with the Australians penetrating from the east, while British troops came from the opposite direction. The 14th Brigade, from the 5th Division, also filled a supporting role, securing flanking positions to the north of the town. In early May, the 12th Brigade carried out a follow up attack around Monument Wood, to the east of Villers-Bretonneux, which made little headway against the defending Jager troops; nevertheless, the recapture of Villers-Bretonneux had restored the Allied line in the sector.