Dec. 7 has never been an ordinary day for Takeo Iguchi. On that day 73 years ago, when Imperial Japanese Navy warplanes attacked Pearl Harbor, he was in Washington, the 11-year-old son of Sadao Iguchi, counselor at the Japanese Embassy there.

Takeo Iguchi, himself a former ambassador to New Zealand and a professor emeritus at Shobi University, has devoted his research to reversing a prevalent view in Japan that it was due to the embassy’s neglect that Japan’s final memorandum was handed to U.S. Secretary of State Cordell Hull at 2:20 p.m. on Dec. 7, 1941, Washington time — one hour after the start of the attack — and thus giving Japan the disgrace of launching a “sneak attack.”

Reiterating the theme of his 2010 book “Demystifying Pearl Harbor — A New Perspective from Japan” (International House of Japan), Iguchi, 84, said in a recent interview that the Japanese army, which wanted its attack on Kota Bharu on the Malay Peninsula and the navy’s attack on Pearl Harbor to be carried out without prior warnings, “caused the Foreign Ministry’s delay in the transmission of a telegram containing the concluding and crucial part of the memorandum in order to protect the secrecy of the Pearl Harbor attack.”

The telegram arrived at the embassy only around 7:30 a.m. Dec. 7. He noted that none of the telegrams containing the memorandum text was labeled urgent, much less of the utmost urgency. At around 10 a.m., the embassy received a telegram ordering it to deliver the memorandum to the U.S. side at 1 p.m. — 20 minutes before the start of the attack. Iguchi also stressed that the telegrams were characterized by numerous garbled parts and missing words, making typing work at the embassy difficult.

Iguchi also said the widely accepted view has had the effect of hiding the important fact that the final memorandum did not conform to the accepted form of an ultimatum making clear Japan’s intention of terminating negotiations and entering into war.

“As a diplomat-historian with living memory of the tragic Pacific War, I had a duty to devote my work to sincerely reassessing the question of Japan’s ultimatum question and subsequent explaining away of the delayed delivery of the memorandum, since the truth has been obfuscated for nearly 70 years by multiple hands and it is high time to rectify misunderstandings surrounding this singular event in order for world historians to obtain a correct historical perspective,” Iguchi said. His effort to correct the prevailing view is finally bearing fruit.

In recent years, new discoveries have confirmed that military leaders deliberately tried to delay the delivery of Japan’s final memorandum to the U.S., thus confusing the embassy in Washington. After the war, experts felt strongly inclined to blame the delay on embassy staff.

In 2013, professor Munehiro Miwa, a director at Kyushu University’s Manuscript Library, discovered a document in the Japanese National Archives that sheds light on questionable moves by military elements at the postwar International Military Tribunal for the Far East.

In September, Iguchi typed out the document — a draft of guidelines for defending military and Foreign Ministry defendants at the tribunal that Miwa thinks was written mainly by lawyers for the navy defendants — and submitted it to the Foreign Ministry, asking that it closely examine what it and the military did in connection with the Pearl Harbor attack.

At the outset, the defense guidelines, dated May 7, 1947, say the lawyers should stress that the navy made an effort so that Japan would deliver an ultimatum expressing its war intention to the U.S. in conformity with international law. They also say the lawyers should make efforts to prevent the conflict among the Foreign, Army and Navy ministries in writing the final memorandum from surfacing at the tribunal.

The guidelines further say the lawyers should argue that Japan believed that in view of the prevailing circumstances at the time, the final memorandum served in substance as an ultimatum expressing the nation’s intent to go to war.

In February 1999, Iguchi unearthed the “Draft Final Memorandum of the Imperial Government Addressed to the U.S. Government,” written by Kumaichi Yamamoto, head of the Foreign Ministry’s American Affairs Bureau, and dated Dec. 3, 1941, in the Foreign Ministry’s Diplomatic Record Office.

The concluding paragraph of the draft reads: “The government of the United States of America has not shown even the slightest degree of sincerity in the current negotiations, and the Japanese government regrets to have to solemnly notify hereby your government that we are forced to terminate negotiations, recognizing that continuation of talks will in no way contribute to the stability of East Asia, and that you will be held responsible for any and all the consequences that may arise in the future.”

But in the memorandum Ambassador Kichisaburo Nomura and special envoy Saburo Kurusu delivered to Hull, the last paragraph was changed to: “The Japanese government regrets to have to notify hereby the American government that in view of the attitude of the American government, it cannot but consider that it is impossible to reach an agreement through further negotiations.”

Iguchi said the change turned the final memorandum into something that was not an ultimatum, fueling anger that Japan carried out a “treacherous attack,” as termed by the U.S.

The tribunal defense guidelines imply that the military exerted pressure to change the last paragraph of the final memorandum. They say the tribunal lawyers should avoid giving the impression that the final memorandum became a vague statement under the pressure of the military and contrary to the will of Foreign Minister Shigenori Togo.

“The defense guidelines show that the Japanese army and navy’s defense counsel beseeched and succeeded in prevailing over the Foreign Ministry’s position and exempted military leaders’ culpability for submitting to the U.S. a misleading final note hiding its intent of declaring war,” Iguchi said. “They also show that the army deleted the concluding and crucial part of the original draft and the navy silently accepted it without protesting.”

He said that minutes kept by Hajime Sugiyama, chief of the Army General Staff, substantiates his view.

Adm. Isoroku Yamamoto, commander in chief of the Combined Fleet for the Imperial Japanese Navy, believed Japan should deliver to the U.S. an advance warning of military action. And there is a view among experts that he told Emperor Hirohito (posthumously known as Emperor Showa) that such a warning would be handed to the U.S. Iguchi, who read a relevant part of the recently issued annals of Emperor Hirohito, however, says that it contains nothing that shows that Yamamoto made such a remark to the Emperor.

“They met for only about 10 minutes. There was no time and no power for Yamamoto to discuss the final memorandum and the method and time of its delivery with the Emperor,” Iguchi said.

The defense guidelines instruct the lawyers to argue that the delay in the delivery of the final memorandum to the U.S. side was due to slow work at the Japanese Embassy in Washington and contrary to Tokyo’s wishes.

“The circumstances clearly show there was no deliberate attempt on the part of the embassy to delay the delivery,” Iguchi said angrily. “The defense guidelines tried to make the embassy bear total responsibility. This is untenable even from a legal viewpoint.”

Kyushu University’s Miwa found documents in the U.S. National Archives in 2012 showing that the Foreign Ministry delayed the transmission of the telegram containing the concluding part of the final memorandum by more than 15 hours from the originally scheduled 1 a.m. to 4:38 p.m. on Dec. 7, 1941, Japan time. It also sent two other telegrams correcting garbled parts and missing words at 175 places in another, earlier telegram containing the remaining parts of the final memorandum as late as 2:20 p.m. and 3:32 p.m. on Dec. 7 Japan time. Miwa said the defense guidelines imply that the navy was not told about the delay in transmitting the telegram containing the concluding part of the final memorandum.

The guidelines for the defense tell the lawyers to argue that the army’s landing on Kota Bharu one hour and 50 minutes before the Pearl Harbor attack were due to miscommunication among the government, the military’s central commands and commands outside Japan.

Both Iguchi and Miwa said that this is contrary to historical fact. Both the army and navy commands knew in advance that instead of the desired simultaneous attacks, the navy would start the Pearl Harbor attack 90 minutes after the Kota Bharu attack because of the lack of predawn-attack experience among the pilots of two aircraft carriers — the Shokaku and the Zuikaku.

“The defense guidelines show that our military leaders narrowly escaped the imputation of a deliberate unannounced attack and the military subjugated and sacrificed our diplomacy to serve its strategic convenience,” Iguchi said. “The Foreign Ministry should closely examine the related facts and provide to the people a truthful account of policy decisions and their execution related to Japan’s diplomatic behavior at the start of the Pacific War.”