Records of Imperial Navy’s Lectures to Emperor Showa Discovered; Military Leaders Sought to Instill Distrust in U.K., U.S.

The Yomiuri Shimbun

15:06 JST, July 14, 2025

Records of lectures on military science given to Emperor Showa by a top naval officer before the Pacific War have been found.

The annals of Emperor Showa, which were compiled by the Imperial Household Agency, notes that such lectures were given to the emperor. However, this is the first time that records of them have been discovered.

The records comprise 22 lectures held from February 1934 to October 1935. The lectures were given by Takayoshi Kato (1883-1955), son-in-law of former Prime Minister Tomosaburo Kato. The younger Kato was vice chief of the Imperial Navy General Staff, its second highest rank.

Yasunobu Teshima, associate professor of Ryukoku University who studies naval history, confirmed that the records had been left at the home of Kato’s descendants.

The records include remarks that were apparently intended to sow distrust of Britain and the United States in the emperor, including a claim that the United States was attempting to “overwhelm the Japanese Imperial Navy and conquer the Pacific Ocean.”

“Emperor Showa was cautious that the military would use the lectures to support its own claims and authority,” Teshima said.

According to Takahisa Furukawa, a professor at Nihon University who is known for his research on Emperor Showa, only two sets of comprehensive records of lectures given to the emperor have been found: One comprises transcripts of lectures on international law given by a scholar on the subject during the Taisho era (1912-26), and the other transcripts of lectures on diplomacy given by a diplomat from the mid-1930s until after Japan’s defeat in the war.

“This is the first time that records of military-related lectures have been discovered, which is quite valuable,” Furukawa said.

According to Teshima, the records were prepared by a member of the Naval General Staff who was in charge of defense and operational planning in the Imperial Navy, indicating that the content of the lectures reflected its views.

The Washington and London naval treaties, both of which were signed to restrict armaments, were set to expire at the end of 1936, and the Imperial Navy was eager to scrap them to build up its armaments.

In June 1934, two lectures were given titled “The international situation as seen by the Imperial Navy,” in which the Naval General Staff’s detailed explanations were designed to instill distrust of Britain and the United States in Emperor Showa. The lectures emphasized that Britain was inherently expansionist, stating, “The country has an ambition to become the world’s largest naval power.”

With regard to the United States, the records assert that the country was aiming to expand its navy for the purpose of advancing into the Orient, overwhelming the Japanese Imperial Navy, dominating the Pacific Ocean and monopolizing the Far Eastern market.

The 11th lecture was held in January 1935 after preliminary negotiations between Japan and the world powers had broken down and Japan had announced its abandonment of the Washington Naval Treaty. The reason for the breakdown was explained in the lecture as follows: “The United States cannot wake up from the old international conception that it should maintain its own vested superiority and oppress the Empire of Japan.”

Ultimately, however, Emperor Showa “did not uncritically accept the claims of the Naval General Staff, because of his ideas of engaging in cooperative diplomacy with Britain and the United States, ideas which had been formed through his visit to Europe when he was crown prince, and lectures on diplomatic history,” according to Teshima.

In fact, although the naval treaties were scrapped, the emperor held on to his idea of cooperating with the two powers.