When the German Spring Offensive opened on 21 March, 47th Division had just relieved another formation in the line and were holding the right flank of Third Army. The main blow fell on Fifth Army to the south, but the Londoners were heavily bombarded and later in the day the Germans attacked behind a smoke screen. 1/19th took part in the successful counter-attack to regain the positions lost. However, Fifth Army was collapsing and 47th Division, with its flank open, was obliged to fall back on successive lines of half-dug trenches. The retirement, with rearguards contesting the German advance throughout, went on for six days and casualties were heavy. By the end, the remnants of 1/19th and 1/20th Londons were formed into a composite battalion.