Japan enters French Indochina

On the afternoon of 22 September 1940 in Hanoi, General Maurice Martin, commander of the French forces in French Indochina, and the Japanese Major General Issaku Nishihara, head of the Japanese military mission in the colony, signed a military agreement. Vichy France consented to the stationing of up to 6,000 Japanese troops in Tonkin, the northern part of the colony, to Japanese use of several airfields there, and to the passage through Tonkin of Japanese troops fighting in China. About seven and a half hours remained before the Japanese ultimatum expired. A few hours later, at precisely 10 p.m. local time, columns of the Japanese 5th Division, stationed in the Chinese province of Guangxi, crossed the border near the fort of Đồng Đăng and advanced on Lạng Sơn. Their commander had no intention of waiting for the peaceful entry the agreement provided for. So began four days of fighting, at the end of which Japan stood in northern Indochina.

It is often said that on this day the Japanese “occupied French Indochina” and the local French officials became mere figureheads. That is a simplification. In September 1940 Japanese troops entered only Tonkin, and in limited numbers. The French administration, army and police continued to function throughout the colony, and the Governor-General, Admiral Jean Decoux, governed it until 9 March 1945, when the Japanese overthrew it by force. Japan nevertheless gained what it needed: the closing of the border with China, bases in Tonkin and its first foothold in South-East Asia.

The Haiphong railway

Since 1937 Japan had been waging a war in China that it did not know how to end. After losing the coast, Chiang Kai-shek’s government in Chongqing received arms and fuel from abroad by several routes, and the most important of them ran through French Indochina: goods were unloaded at the port of Haiphong, from where a railway ran through Hanoi and Lào Cai to Kunming, the capital of Yunnan province. A second branch, from Hanoi through Lạng Sơn, reached the Guangxi border. The French, not wishing to provoke Japan, formally restricted the transit of arms, but the traffic continued, since French, British and American merchants were also profiting from it. The Japanese took Nanning in November 1939 and reached the border pass in Guangxi, and their aircraft bombed the railway in Yunnan, but they did not cut the line from Haiphong to Kunming.

The decisive turn came with France’s defeat in Europe. In mid-June 1940 the Indochinese authorities banned the export of arms, fuel and lorries to China, and when on 19 June Japan demanded, within twenty-four hours, the closing of the border and the admission of its observers, the Governor-General, General Georges Catroux, gave way on 20 June without seeking the government’s approval. He knew that the colony would receive no help either from France, which was at that very moment asking for an armistice, or from Britain, to which he had appealed in vain. On 29 June Nishihara’s mission arrived in Hanoi, and the Japanese demands quickly grew: from supervision of the border to airfields and the right of passage for troops.

The government of Marshal Philippe Pétain considered Catroux’s unauthorised action unacceptable and by a decree of 25 June appointed in his place Vice-Admiral Jean Decoux, commander of the French naval squadron in the Far East. Decoux took office on 20 July. Instead of returning to France, Catroux joined Charles de Gaulle. The new governor knew that he could not defend the colony: he had about 32,000 regular troops and some ten to twenty thousand auxiliaries, obsolete artillery and fewer than a hundred aircraft. He hoped, however, that resistance would be enough to deter Japan from risking open war, and he urged Vichy to reject the demands.

Negotiations under pressure

In Tokyo the decision had already been taken. The programme of Prince Fumimaro Konoe’s second government, adopted at the end of July, envisaged forcing Indochina to halt the transit to China and to grant rights of passage and the use of airfields, and, if necessary, the use of force. As early as June the Foreign Minister, Hachirō Arita, had declared that the fate of the South Seas was a matter of “grave concern” to Japan. His successor, Yōsuke Matsuoka, conducted talks with the French ambassador in Tokyo, Charles Arsène-Henry. On 30 August 1940 the two signed an agreement: France recognised the “pre-eminence” of Japanese interests in the Far East and agreed to grant Japanese forces facilities in Tonkin for the duration of the war with China, while Japan recognised French sovereignty over Indochina and its territorial integrity. The details were to be settled on the spot by the military.

The talks between Martin and Nishihara began in Hanoi on 3 September and went badly. Decoux played for time and asked the Americans and the British for arms, while Vichy tried in vain to get Germany to restrain its Japanese partner. The Japanese army was divided. The General Staff in Tokyo wanted a peaceful entry, but the head of its operations section, Major General Kyōji Tominaga – the same man who a year earlier had pushed through the attack on Nanning, and who had now been sent to Indochina – together with officers of Lieutenant General Rikichi Andō’s South China Area Army, sought a show of force. On 6 September a battalion of the Japanese 22nd Army crossed the border near Đồng Đăng. The Japanese explained this as a mistake over the terrain; the French broke off the talks. Tominaga demanded the admission not of 6,000 but of 25,000 troops. On 18 and 19 September the Japanese delivered an ultimatum: if no agreement was concluded, their troops would enter Indochina at midnight on 22/23 September Tokyo time, that is at 10 p.m. Hanoi time. Decoux demanded a reduction in the Japanese contingent, and on 21 September Nishihara, with the backing of Imperial General Headquarters, returned to the figure of 6,000 troops. The next day Martin and Nishihara signed the agreement.

Some summaries speak of a “Decoux–Nishihara” agreement. Decoux approved it, but the signatures were those of Martin and Nishihara, and historians know it under their names (in Japan as the Nishihara–Martin agreement). Some studies date the agreement to 20 September, when its text was settled. It provided for the stationing of up to 6,000 Japanese in Tonkin north of the Red River; the use of three or four airfields (sources differ on the details, naming among others Gia Lâm near Hanoi, Lào Cai and Phủ Lạng Thương); the passage through Tonkin to Yunnan of up to 25,000 troops; and the transport of one division from Guangxi through Haiphong. The first units were to arrive by sea: as early as 5 September Major General Takuma Nishimura’s Indochina Expeditionary Army had been formed, and its convoy was waiting off the coast of Hainan.

The attack at Đồng Đăng and Lạng Sơn

News of the signing reached the headquarters at 9 p.m. Even so, at 10 p.m. the commander of the 5th Division, Lieutenant General Aketo Nakamura, sent his columns across the border at three points. Japanese sources give the same moment as midnight on 23 September, because they reckon in Tokyo time. Nakamura had his superiors’ tacit approval. Tominaga, dissatisfied that the agreement had been concluded on more modest terms than he had demanded, left without issuing an order to halt the advance. The headquarters of the South China Area Army ignored a telegram from the General Staff calling off the overland march, because it did not have the form of an order from Imperial General Headquarters, and Nakamura disregarded Nishihara’s message that the agreement had been concluded.

The French had orders to resist anyone who crossed the border without consent. Near Đồng Đăng an exchange of fire broke out, which during the night spread to further posts. On the morning of 23 September the Japanese attacked the fort of Đồng Đăng. At about 11 a.m. the defence collapsed and its commander was killed. That day the Vichy government protested in Tokyo against the breach of the agreement, and that night the General Staff issued a formal order to halt the advance. It nevertheless permitted “local” acts of self-defence, which the 5th Division interpreted broadly, and it pressed on. On 23 September the American Secretary of State, Cordell Hull, declared that the United States would not recognise a change in the status quo in Indochina brought about under threat.

The main fighting took place around Lạng Sơn, a railway and road junction some fifteen kilometres from the border, held by General Germain Mennerat’s 2nd Brigade of the Tonkin Division – about 5,000 men of the colonial infantry, Tonkinese rifles and the 5th Infantry Regiment of the Foreign Legion. The Japanese, more numerous and with tanks and air support, surrounded the town. The French command, misled by intelligence reports that the enemy was exhausted, failed to stop them, and some of the local troops deserted. On the morning of 25 September, after an artillery bombardment, Mennerat reported that the position could not be held and, with Martin’s consent, capitulated. Before laying down their arms the French threw the breech blocks of their 155 mm guns into the river. Among those taken prisoner was a Legion battalion in which 179 Germans and Austrians were serving; the Japanese tried without success to persuade them to change sides.

Also on 25 September Decoux, convinced that further resistance would cost France the whole colony, ordered a ceasefire, and an order to cease fire also came from Tokyo. Some chronologies state that on this day the 5th Division “entered Hanoi”. The sources do not confirm this: on 25 September the division took Lạng Sơn and halted there. Japanese garrisons were installed in Hanoi and at the nearby Gia Lâm airfield only after the fighting had ended, under the terms of the agreement.

The landing near Haiphong

Nishimura’s convoy, which arrived in the Gulf of Tonkin on 24 September, was refused permission by the French to unload in the port. On the morning of 24 September aircraft from the carrier Hiryū began reconnaissance and intimidation flights over the French positions on the coast. An envoy of Decoux’s went aboard a Japanese warship for talks, but the coastal batteries had orders to open fire on anyone attempting to land. At about 3.30 a.m. on 26 September the Japanese – some 4,500 troops with a dozen or so tanks – landed on the beach at Đồng Tắc, south of Haiphong, and advanced on the city (some chronologies give 25 September here). At about 6.30 a.m. Japanese aircraft bombed Haiphong, killing 37 civilians according to French sources. The French did not resist, and by the evening of 26 September the fighting had ceased.

The Japanese occupied Gia Lâm airfield, the station at Lào Cai on the Yunnan border and Phủ Lạng Thương on the line from Hanoi to Lạng Sơn, and stationed about 900 troops in Haiphong and 600 in Hanoi. The tally of losses is uncertain. The detailed report of the 5th Division gives 71 killed and 230 wounded on the Japanese side (another Japanese document gives 67 killed and 205 wounded). Japanese reports estimated enemy losses at 408 killed and 2,216 French and Indochinese soldiers taken prisoner, while Western studies put French losses at around 800–900 men.

Punishment without consequences

In Tokyo the entry into Indochina, which was supposed to have been peaceful, was regarded as a scandal. Nishihara sent a telegram to the vice-ministers of war and the navy: “The command is in disarray; we have lost trust at home and abroad.” The War Minister, General Hideki Tōjō, who had earlier agreed to preparations for an entry by force, now treated the insubordination as an infringement of the imperial prerogative of command. Tominaga, recalled on 25 September, lost his post on the General Staff; Andō and Nakamura were transferred to the reserve, and other officers were also punished. All of them later returned to service. On 5 October the Japanese formally apologised for the “Lạng Sơn incident”, released the prisoners and handed the town back to the French.

Yet they had achieved their aim. The railway from Haiphong to Kunming was closed to supplies for China, and Japan gained airfields from which it could bomb Yunnan. In the autumn the Japanese withdrew from Nanning and southern Guangxi, which they no longer needed to hold once the Indochinese border was closed. In Indochina the French began to have trouble with the local population. Vietnamese nationalists of the National Restoration Army, who had entered Tonkin alongside the Japanese, were abandoned by them when Lạng Sơn was returned to the French, and a communist uprising in the Bắc Sơn district at the end of September was put down by the French.

Place in the war

The entry into Tonkin was Japan’s first step into South-East Asia and showed how weak Vichy France had become in its colonies. It coincided with decisions that settled the course of relations with America. On 26 September President Franklin Delano Roosevelt announced an embargo on exports of scrap iron and steel to Japan (from 16 October), and on 27 September Japan signed the Tripartite Pact with Germany and Italy in Berlin. In October Britain reopened the Burma Road, which became the main route for aid to China.

Thailand, too, exploited France’s weakness. The Franco-Thai War of 1940–1941 ended, despite the French naval victory at Ko Chang, with the loss of parts of Laos and Cambodia, forced on France through Japanese “mediation”. In July 1941 Japan moved into southern Indochina, which the United States, Britain and the Netherlands regarded as preparation for an attack on Malaya and the Dutch East Indies; they responded by freezing Japanese assets and imposing an oil embargo. From bases in Indochina the Japanese struck at Malaya in December 1941, and their aircraft sank the British warships Prince of Wales and Repulse.

The French administration survived until the coup of 9 March 1945, when the Japanese interned Decoux and the French troops and Emperor Bảo Đại proclaimed Vietnam’s independence under Japanese tutelage. Dual French and Japanese rule, Japanese requisitions of rice and Allied bombing contributed to the famine in northern Vietnam in 1944–1945, whose victims are estimated at anywhere from several hundred thousand to two million people. After Japan’s surrender the Việt Minh took power, and the return of the French led in 1946 to the Indochina War.