At the outbreak of World War II "Athos II" was still on the Far Eastern route but on 1 February 1940 at Colombo, Celyon joined the Australian/New Zealand convoy, designated US1 for secrecy and transporting about 13,500 troops to North Africa, under an escort then led by . After passage through the Suez Canal and return to France "Athos II" began Marseilles, Egypt and Syria service until the 22 June 1940 German-French armistice when the ship was laid up at Alexandria, Egypt along with other French ships seized in the Suez Canal and Egyptian waters. In addition to the merchant ships was a French naval force, Force X, under Admiral Rene-Emile Godfroy that had been operating with the British fleet out of Alexandria. After the fall of France with German controlled Vichy France controlling French ports the French were faced with the options of continuing with the Allies under General de Gaulle, demilitarizing or being sunk by the British. The British action against the French fleet at Oran stalled demilitarization but that resumed after further negotiations with the result reduction of French fleet's manpower, some 4,000 men, to one-third was required. Two thousand French sailors had already left Alexandria when "Athos II" was allowed to sail on 13 July 1940 with the 1,000 remaining personnel of Force X and some merchant crew members to France. In September 1940 repatriated French troops from Syria and then became the guard ship at Algiers until captured by the Allies in November 1942 during Operation Torch.