Mezue ahịrịokwu na-esonụ: Cassels jere ozi na Agha Worldwa nke Abụọ, ebe ọ na-eje ozi n'England, ọ gara ọmụmụ ihe dị mkpirikpi na Staff College, Camberley. Na Mee 1940 ọ ghọrọ onye isi ndị agha na ndị agha Territorial Army (TA), 157th Infantry Brigade, nke Brigadier Sir John Laurie, onye bụbu onye isi ndị agha Cassels (CO) na 2nd Seaforths, bụ akụkụ nke Major General James Drew's 52nd (Lowland) Infantry Division, nke e zigara na France na June 1940 iji kwado ndị agha France na mgbe British Expeditionary Force (BEF) si Dunkirk pụọ. Ndị agha Cassel, nke mbụ n'ime ndị agha nke 52nd nke bịarutere France, bụ, n'oge na-adịghị anya mgbe ọ bịarutere, nyere iwu ka ha mepụta ikike nke ndị agha French nke iri na Conches, Normandy. Otú ọ dị, e lere ọnọdụ ahụ anya dị ka enweghị olileanya na ndị agha Cassel mechara wepụ site na Cherbourg na 18 June. Ndị France bịanyere aka na
nkwekọrịta nke abụọ nke Compiègne ụbọchị ole na ole mgbe nke ahụ gasịrị.