He presided over the Japanese invasion of China in 1937 and breakdown in relations with the United States, which shortly after his tenure culminated in Japan's entry into World War II.

When the Marco Polo Bridge Incident took place a month later, he oversaw an escalation of tensions with the Republic of China which ultimately culminated in the Second Sino-Japanese War.

During the early years of the conflict, Konoe presided over a series of crushing victories against Chinese forces as well as the perpetration of numerous atrocities (including the Nanjing Massacre).

In 1938, he enacted the State General Mobilization Law which massively expanded the government's control over Japanese civilians in order to place the country on a war footing.

Later that year, he founded the Imperial Rule Assistance Association and oversaw the signing of the Tripartite Pact with Nazi Germany and Fascist Italy.

During his second premiership, Konoe also presided over the Japanese invasion of French Indochina, the formal recognition of Wang Jingwei's puppet government in Nanjing and the conclusion of the Soviet–Japanese Neutrality Pact.

Despite attempting to resolve growing tensions with the United States, a rigid timetable imposed by the military on the negotiations and Konoe's own inflexibility set the two countries on the path to war.

Konoe remained a close advisor to Emperor Hirohito until the end of World War II and played a key role in the fall of the Tōjō Cabinet in 1944.

At the start of the Allied occupation of Japan in 1945, he briefly served as a minister in the cabinet of Prince Naruhiko Higashikuni, but came under suspicion of war crimes.

[10] After graduation, Fumimaro turned to Saionji for advice about starting a political career, and worked briefly in the home ministry before accompanying his mentor to Versailles as part of the Japanese peace delegation.

[17] Upon his return to Japan he published a booklet where he described his travels to France, Britain and the U.S. Konoe noted how he was angered by rising anti-Japanese sentiment in the United States and how the US government discriminated against Japanese immigrants.

These officials also shared Konoe's concern about party influence within the home ministry, which had seen great turnover mirroring the political upheaval occurring in the Diet.

[30] The Association for Election Purification (Senkyo Shukusei Dōmeikai) was also created, an organization whose purpose was to circumvent and weaken pork-barrel local politics by supporting candidates that were not beholden to meiboka bosses.

In a speech in 1935, Konoe said that the "monopolization" of resources by the Anglo-American alliance must end and be replaced by an "international new deal" to help countries like Japan take care of their growing populations.

Konoe opposed immediate peace negotiations, and instead chose to escalate the war by suggesting deliberately humiliating terms that he knew Chiang Kai-shek would never accept[neutrality is disputed] in order to win a "total victory" over China.

[47][additional citation(s) needed] In January 1938, Konoe issued a statement declaring that Kuomintang aggression had not ceased despite its defeat, that it was "subjecting its people to great misery", and that Japan would no longer deal with Chiang.

Despite this response, foreign minister Yosuke Matsuoka signed the Tripartite Pact on 27 September 1940, over the objection of some of Konoe's advisors, including former Japanese ambassador to the U.S. Kikujiro Ishii.

[55] In November 1940, Japan signed the Sino-Japanese treaty with Wang Jingwei, who had been a disciple of Sun Yat-sen and headed a rival Kuomintang government in Nanjing.

[58] In February 1941 Konoe chose Admiral Kichisaburō Nomura as Japanese ambassador to the U.S.[41] Matsuoka and Stalin signed the Soviet–Japanese Neutrality Pact in Moscow on 13 April 1941, which made it clear that the Soviets would not help the Allies in the event of war with Japan.

[61] The outline of the proposal, which had been drafted in consultation with banker Tadao Ikawa, Colonel Hideo Iwakura, and Nomura, included American recognition of Manchukuo, the merging of Chiang's government with the Japanese-backed Reorganized National Government of China, normalization of trade relations, withdrawal of Japanese troops from China, mutual respect for Chinese independence, and an agreement that Japanese immigration to the United States would proceed on the basis of equality with other nationals free from discrimination.

After arguing that Japan should let Germany see this draft, he left the meeting, citing exhaustion, Konoe also retreated to his villa, also claiming a fever, instead of forcing the issue.

[64] Matsuoka changed the U.S. draft into a counteroffer that essentially gutted most of the Japanese concessions in regard to China and expansion in the Pacific and had Nomura deliver it to Washington.

[69] Matsuoka was convinced that Operation Barbarossa would be a quick German victory, and he was now opposed to attacking Singapore because he believed it would provoke war with the western allies.

Beginning on 10 July, Konoe held a series of liaison conferences to discuss the Japanese response to Hull's latest amendment to the draft of understanding.

[86] On 5 September, Konoe met the emperor with chiefs of staff General Hajime Sugiyama and Admiral Osami Nagano to inform him of the cabinet's decision to commit to war in the absence of a diplomatic breakthrough.

[88] On 6 September, the Emperor approved the cabinet's decision at an imperial conference after being given assurance by the two chiefs of staff that diplomacy was the primary emphasis, with war only as a fall-back option in the event of diplomatic failure.

[92] On 10 September, Nomura met with Hull, who told him that the latest Japanese offer was a non-starter and that Japan would have to make concessions in regard to China before the summit meeting could take place.

[94] At the liaison conference of 25 September, sensing that summit negotiations were stalling, Tojo and the militarists pressed the cabinet to commit to an actual deadline for war of 15 October.

[97] At the 4 October liaison conference, Hull's response was still being processed and could not be fully discussed; Nagano changed his position and now agreed with the army and advocated a deadline for war.

In 1946, Hirohito explained this decision: "I actually thought Prince Higashikuni suitable as chief of staff of the Army; but I think the appointment of a member of the imperial house to a political office must be considered very carefully.