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War: advance and retreat

On 8 December (7 December in Hawaii), 1941, in simultaneous attacks, Japanese forces struck at the Hong Kong Garrison, the US Fleet in Pearl Harbor and in the Philippines, and began the invasion of Malaya.

With the nation fully committed to the war, Hirohito took a keen interest in military progress and sought to boost morale. According to Akira Yamada and Akira Fujiwara, Hirohito made major interventions in some military operations. For example, he pressed Sugiyama four times, on 13 and 21 January and 9 and 26 February, to increase troop strength and launch an attack on Bataan. On 9 February 19 March, and 29 May, Hirohito ordered the Army Chief of staff to examine the possibilities for an attack on Chongqing in China, which led to Operation Gogo.

While some authors, like journalists Peter Jennings and Todd Brewster, say that throughout the war, Hirohito was "outraged" at Japanese war crimes and the political dysfunction of many societal institutions that proclaimed their loyalty to him, and sometimes spoke up against them, others, such as historians Herbert P. Bix and Mark Felton, as well as the expert on China's international relations Michael Tai, point out that Hirohito personally sanctioned the " Three Alls policy " (Sankō Sakusen), a scorched earth strategy implemented in China from 1942 to 1945 and which was both directly and indirectly responsible for the deaths of "more than 2.7 million" Chinese civilians.

As the tide of war began to turn against Japan (around late 1942 and early 1943), the flow of information to the palace gradually began to bear less and less relation to reality, while others suggest that Hirohito worked closely with Prime Minister Hideki Tojo, continued to be well and accurately briefed by the military, and knew Japan's military position precisely right up to the point of surrender. The chief of staff of the General Affairs section of the Prime Minister's office, Shuichi Inada, remarked to Tōjō's private secretary, Sadao Akamatsu:

There has never been a cabinet in which the prime minister, and all the ministers, reported so often to the throne. In order to effect the essence of genuine direct imperial rule and to relieve the concerns of the Emperor, the ministers reported to the throne matters within the scope of their responsibilities as per the prime minister's directives... In times of intense activities, typed drafts were presented to the Emperor with corrections in red. First draft, second draft, final draft and so forth, came as deliberations progressed one after the other and were sanctioned accordingly by the Emperor.

In the first six months of war, all the major engagements had been victories. Japanese advances were stopped in the summer of 1942 with the battle of Midway and the landing of the American forces on Guadalcanal and Tulagi in August. Hirohito played an increasingly influential role in the war; in eleven major episodes he was deeply involved in supervising the actual conduct of war operations. Hirohito pressured the High Command to order an early attack on the Philippines in 1941–42, including the fortified Bataan peninsula. He secured the deployment of army air power in the Guadalcanal campaign. Following Japan's withdrawal from Guadalcanal he demanded a new offensive in New Guinea, which was duly carried out but failed badly. Unhappy with the navy's conduct of the war, he criticized its withdrawal from the central Solomon Islands and demanded naval battles against the Americans for the losses they had inflicted in the Aleutians. The battles were disasters. Finally, it was at his insistence that plans were drafted for the recapture of Saipan and, later, for an offensive in the Battle of Okinawa. With the Army and Navy bitterly feuding, he settled disputes over the allocation of resources. He helped plan military offenses.

In September 1944, Hirohito declared that it must be his citizens' resolve to smash the evil purposes of the Westerners so that their imperial destiny might continue, but all along, it is just a mask for the urgent need of Japan to scratch a victory against the counter-offensive campaign of the Allied Forces.

On October 18, 1944, the Imperial headquarters had resolved that the Japanese must make a stand in the vicinity of Leyte to prevent the Americans from landing in the Philippines. This view was widely frowned upon and disgruntled the policymakers from both the army and navy sectors. Hirohito was quoted that he approved of such since if they won in that campaign, they would be finally having a room to negotiate with the Americans. As high as their spirits could go, the reality check for the Japanese would also come into play since the forces they have sent in Leyte, was practically the ones that would efficiently defend the island of Luzon, hence the Japanese had struck a huge blow in their own military planning.

The media, under tight government control, repeatedly portrayed him as lifting the popular morale even as the Japanese cities came under heavy air attack in 1944–45 and food and housing shortages mounted. Japanese retreats and defeats were celebrated by the media as successes that portended "Certain Victory." Only gradually did it become apparent to the Japanese people that the situation was very grim due to growing shortages of food, medicine, and fuel as U.S. submarines began wiping out Japanese shipping. Starting in mid 1944, American raids on the major cities of Japan made a mockery of the unending tales of victory. Later that year, with the downfall of Tojo's government, two other prime ministers were appointed to continue the war effort, Kuniaki Koiso and Kantarō Suzuki —each with the formal approval of Hirohito. Both were unsuccessful and Japan was nearing disaster.