Vichy vs. Japan vs. Vietnam, 1940

From Embers of War: The Fall of an Empire and the Making of America's Vietnam, by Fredrik Logevall (Random House, 2012), Kindle pp. 59-60:

On August 29, Vichy concluded an agreement with Japan that recognized Japan’s “preeminent position” in the Far East and granted Tokyo special economic privileges in Indochina. Japan also received transit facilities in Tonkin, subject to agreement between the military officials on the spot. In exchange, Japan recognized the “permanent French interests in Indochina.” Negotiations continued in Hanoi in September and went slowly, as French negotiator General Maurice Martin held out hope for an American naval intervention that would cause Japan to scale down her demands. Increasingly impatient, the Japanese warned Martin that Japanese troops from the Twenty-second Army, based in Nanning, would enter Indochina at 10 P.M. on September 22, whatever the outcome of the negotiations. At 2:30 P.M. on the twenty-second, the negotiators signed an agreement authorizing the Japanese to station 6,000 troops in Tonkin north of the Red River; to use three Tonkin airfields; and to send up to 25,000 men through Tonkin into Yunnan in southern China.

The agreement stipulated that the first Japanese units would arrive by sea. But the Twenty-second Army was intent on moving its elite Fifth Infantry Division across the Chinese border near Lang Son at precisely 10 P.M. Not long after crossing the frontier, the Japanese units became engaged in a fierce firefight near the French position at Dong Dang. Almost immediately, skirmishing also began at other frontier posts. For two days the battle raged, with the key French position of Lang Son falling on the twenty-fifth. The French forces had suffered a major defeat—two posts were gone, casualties were significant (estimates run to 150 dead on the French side), and hundreds of Indochinese riflemen deserted in the course of the battle. It might have been much worse had not Decoux and Baudouin appealed directly to Tokyo and had not the emperor personally ordered his troops to halt their advance. The Japanese apologized for the incident and termed it a “dreadful mistake,” but they had made their point: Governor-General Decoux and the French might still be the rulers of Indochina, but they operated at the mercy of Japan.

Decoux did his best to pretend otherwise. To anyone who would listen, he claimed that the Japanese were not an occupying force but were merely stationed in the country; that the French administration functioned freely and without impediment; and that the police and security services were solely in French hands. The tricolor, he noted, continued to fly over his headquarters in Hanoi. And indeed, French authority in Indochina remained formidable, as Ho Chi Minh and the Indochinese Communist Party learned firsthand in the fall of 1940. Sensing opportunity with the fall of France in June, the ICP in the autumn launched uprisings in both Tonkin and Cochin China against French authorities, only to be brutally crushed. In Cochin China, the French used their few aircraft as well as armored units and artillery to destroy whole villages, killing hundreds in the process. Up to eight thousand people were detained, and more than one hundred ICP cadres were executed. Not until early 1945 would the party’s southern branch recover from this defeat.