When Gort went to command the British Expeditionary Force (BEF), he wanted to take Adam as his chief of staff. Hore-Belisha refused the request on the grounds of maintaining continuity. However, in October 1939 Adam was appointed commander of III Corps, which by February 1940 was crossing the Channel to join the BEF. III Corps was earmarked for operations in Scandinavia, but by April the planned invasion was cancelled when Germany invaded Denmark and Norway, and the Corps remained in France. When in late May, the BEF was ordered to evacuate, Adam was given the task of organising the Dunkirk perimeter; Major General S. R. Wason took over command of III Corps. It was substantially due to Adam's leadership that the BEF was able to retreat behind a strong perimeter and carry out the Dunkirk evacuation. Ordered to leave on 26 May, Adam and Brigadier Frederick Lawson found a canvas boat on the sand dunes and rowed out to a waiting destroyer. For his part, he was mentioned in despatches a fourth time.