Bishii May 1940kii waxaa dalka Belgium soo galay ciidamada Nazi Germany. Ka dib markii ay Belgiumku is dhiibeen iyo bilowgii shaqo joojinta Jarmalka, madaxa POB<unk>BWP Henri de Man wuxuu ku dhawaaqay kala diridda xisbiga shuuciga ah oo qayb ka ah siyaasadda iskaashiga. Van Acker wuxuu ka noqday nolosha bulshada. Sanadkii 1941, si kastaba ha noqotee, wuxuu dib ugu soo biiray xisbiga bulshada ee sharci darrada ah iyo dhaqdhaqaaqa ururka shaqaalaha dhulka hoostiisa ku jira "Monsieur André" wuxuuna ku safray waddanka oo dhan isagoo xiriir la leh qaybaha xisbiga. Xoreynta Belgium
Bishii Sebtember 1944, Van Acker wuxuu u soo baxay madaxa xisbiga dhaxal sugaha POB<unk>BWP, Xisbiga Bulshada ee Belgian ("Belgische Socialistische Partij", PSB-BSP).