Commander-in-chief of the U.S. Pacific Fleet, but it was discounted by everyone involved in Washington, D.C., and Hawaii. Grew served as ambassador until December 8, 1941, when the United States and Japan severed diplomatic relations during the Japanese bombing of Pearl Harbor. All Allied diplomats were later interned. On April 18, 1942, US B-25 bombers flew from an American carrier and carried out the Doolittle Raid of bombing Tokyo and other cities. Grew witnessed the attack while he was interned. When he realized that the low-flying planes over Tokyo were American, not Japanese planes on maneuvers, he thought they may have flown from the Aleutian Islands, as they appeared too large to be from a carrier. Grew wrote in his memoirs that embassy staff were "very happy and proud." In accordance with diplomatic treaties, the US and Japan negotiated the repatriation of their diplomats via neutral territory. In July 1942, Grew and 1,450 other American and foreign citizens went via steamship from Tokyo to Lourenço Marques in Portuguese East Africa aboard the Japanese liner Asama Maru and her backup, the Italian liner Conte Verde. In exchange, the US sent home the Japanese diplomats, along with 1,096 other Japanese citizens. Atomic bomb dilemma Grew wrote in 1942 that he expected Nazi Germany to collapse, like the German Empire in 1918, but not the Japanese Empire: Under Secretary of State (1944–1945) Grew returned to Washington in 1942 and served as a special assistant to Secretary Hull. In 1944, he was promoted to director of the Division of Far Eastern Affairs. From December 1944 to August 1945, he served once again as undersecretary of state. A fierce anticommunist, he opposed co-operation with the Soviets. Roosevelt wanted closer relationships with Joseph Stalin, unlike the new President, Harry Truman. Grew was again appointed as Under Secretary of State and served from December 20, 1944 to August 15, 1945. He served as the Acting Secretary of State for most of the period from January to August 1945, while Secretaries of State Edward Stettinius and James F. Byrnes were away at conferences. Among high-level officials in Washington, Grew was the most knowledgeable regarding Japanese issues. He was also the author of an influential book about Japan, titled Ten Years in Japan. Grew advocated a soft peace that would be acceptable to the Japanese people and would maintain an honorable status for the Emperor. He successfully opposed treating