Rambai muchinyora ndima iyi - Apo mambo akanga achitonga Monivong akafa musi wa 23 April 1941 Gavhuna Mukuru weFrench Indochina, Jean Decoux, akasarudza Sihanouk kuti amutsive. Kusarudzwa kwaSihanouk samambo kwakarongwa zuva rakatevera neCambodian Crown Council, uye kupfekedzwa kwake korona kwakaitika musi wa 3 Chivabvu 1941. Munguva yokugara kweJapan muCambodia
, akapedzera nguva yake yakawanda kumitambo, kutora mafirimu, uye dzimwe nguva kushanya kumaruwa. Muna March 1945 mauto eJapan, ayo akanga apinda muCambodia kubva muna August 1941, akaparadza hurumende yeFrench yekoloni. Vachimanikidzwa nevaJapan, Sihanouk akazivisa kuzvimiririra kweCambodia uye akava mutungamiriri wehurumende uku achishandawo samambo.