In the afternoon of 12 June, Lieutenant Colonel Johnson was ordered to hastily prepare his battalion for an attack on the village of Bréville (currently named Bréville-les-Monts). At 21:45, the battalion assembled on the start line near Amfréville and an artillery barrage on enemy positions near Bréville began.
Lieutenant Colonel Johnson was conferring with a group of senior officers when he was killed by a stray artillery round. Also wounded by the blast were Brigadier Hugh Kindersley and Colonel Reginald Parker of 6th Airlanding Brigade and Brigadier The Lord Lovat of 1st Special Service Brigade.