154th Brigade was luckier than its sister brigades of the 51st Division (152nd and 153rd). It was detached in June 1940 to form the mobile battlegroup "Arkforce" and was able to escape from Northern France while the rest of the division was forced to surrender at St Valery-en-Caux. However, the brigade was severely understrength by the time it returned to Britain, and in August 1940 it was reorganised and merged with the 28th Infantry Brigade of 9th (Highland) Infantry Division to form part of the new 51st Division. In this capacity it went on to serve in North Africa, Sicily and North-West Europe.