Indochina Campaign (1941-1942)

The Indochina Campaign was fought between Allied and Japanese forces in French Indochina from November 14th 1941 to May 12th 1942 during the Pacific War. The campaign consisted mainly of battles in what is now northern Vietnam and was dominated by fighting around the cities of Hanoi and Lang Son. Additional fighting took place in central Vietnam and in the South China Sea. Japanese forces attempted to occupy Indochina in order to subjugate Thailand and outflank British Imperial forces defending Burma.

Naval and land advances against both Hanoi and Saigon were repulsed by allied armies with significant casualties on both sides. Following these reverses, Japanese forces were pushed back by a Franco-German advance to Lang Son where they attempted to mount a defence. After several battle, Allied troops broke through and Japanese forces retreated to southern China.

The Indochina Campaign, coupled with the near simultaneous successful Commonwealth defence of Malaya, represented a severe setback for Japanese military planners. They were denied a base from which to break Commonwealth lines in Burma and support their campaign in the Dutch East Indies and Malaya.

Japanese
By 1941 Japan had been at war with China for four years, attempting its complete occupation. This campaign had lasted past the estimates of the Japanese high command, thanks to fierce Chinese resistance, and was exhausting the country's resources. In an attempt to fuel the war effort, Japan made war on both the British Empire and the Netherlands in 1940 to acquire their resource rich Asian holdings. However, it was forced to operate all the way from tenuously held ports and airbases in Southern China during its attempted invasion of the Dutch East Indies and assault prepared British defences in Burma. Both efforts struggled as a result and Japanese high command decided on an invasion of French Indochina to resolve these issues. Occupying Indochina would grant bases to support the invasion of the East Indies and the planned attack on British Malaya as well as provide a route to sweep into Burma past Commonwealth lines.

Throughout 1941 Japanese forces built up in Southern China in preparation for the campaign. Three divisions as well as several airborne and marine regiments would make up the ground forces supported by 180 modern aircraft including the advanced A6M Zero fighter.

French
Although France had held Indochina since 1887, it was relatively neglected militarily. France had long viewed Europe and Africa as the Empire's most important areas and Asia was thought of as an unimportant backwater. However, Japanese military expansion did concern both the political and military establishment in France resulting in some improvements to the defences of the colony. The esteemed combat commander Joseph Sarrail was placed in in charge of Indochina's garrison in early late 1939 and following a thorough survey, requested more forces to resist a possible invasion. Sarrail called for at least two full infantry divisions equipped with modern tanks, several squadrons of modern fighters and bombers, and a significant improvement in the Indochinese Fleet; he received a fraction of this.

In an attempt to remedy his deficiency in forces he attempted several improvements. Firstly he significantly upgraded the shore defences of both Saigon and Haiphong, the colony's two deep-water ports. Secondly he prepared entrenched defensive positions and bunkers in and around Hanoi. Thirdly he put time into recruiting and training locals who knew the area in guerrilla warfare and scouting. Lastly he made detailed survey's of the waters and islands in the South China Sea.

Several months before the invasion the remnants of the British Garrison of Hong Kong was evacuated to Indochina and a German regiment arrived intended as a symbolic show of support against the Japanese. This left Sarrail a force of six regular regiments plus irregulars and provincial militias, two squadrons of M.S.406 fighters, and 38 WWI-era FT-17 tanks to face the Japanese invaders.

Japanese Advance
On November 12th Japan issued an ultimatum to France, demanding military access to Indochina ostensibly in order to "protect Japanese property and lives from violence." There had been anti-Japanese demonstration in major cities throughout the colony in response to the country's expansionism throughout Asia, but they had been generally peaceful. Despite having limited forces in Asia, King Jean refused the ultimatum and so a state of war was declared on November 14th. The colonial garrison was immediately mobilized and a large force began to be raised in France to assist the colony.

The first military action against France was a bombing raid on the small enclave of Guangzhouwan in southern China. This sunk several ships and killed dozens of civilians. Mere hours later, the Imperial Japanese Army crossed the border from China into Indochina where it skirmished with local irregular guerrilla units. Sarrail knew he had to hold the deep-water ports of Haiphong in the North and Saigon in the South in order to receive reinforcements by sea and deny the enemy the same. Vietnamese guerrilla fighters harassed the IJA as it advanced southwards, holding up its progress and allowing Sarrail time to organize his regulars. Three of the Foreign legion regiments alongside the British and German regiments would hold Hanoi, northern Indochina's infrastructure and transport hub and key to taking Haiphong. This left only a single regular regiment to hold Saigon, Sarrail gambled the main thrust would be towards Hanoi and Haiphong.

Meanwhile, Germany declared war on Japan on the 16th and began evacuating civilians from Guangzhouwan to Indochina. The German Pacific Expeditionary Fleet was severely damaged during the Battle of the Gulf of Tonkin while protecting evacuee transports and was forced to repair at Saigon. In the naval battle, the German Battleship SMS Bismarck, along with one destroyer, risked its life by putting itself in-between a civilian transport column and several Japanese cruisers firing upon them, vowing to protect the German and French ships leaving Guangzhouwan. The Bismarck sunk the Japanese cruiser Agano during the engagement by rupturing its bow and forcing it to capsize, the only ship the Germans sunk in the battle. The Bismarck, which suffered intense damage, including the fatality of more than half of the officers on board when the command bridge was hit by an explosive shell, successfully protected the last of the transport ships and managed to retreat by deploying smoke screens and being covered by the firepower of the already eviscerated SMS Prinz Eugen. The bravery of the German navy that day earned many of the surviving officers of the fleet the Iron Crosses. Although a majority of the civilians escaped the port of Guangzhouwan, French forces were overwhelmed and were forced to capitulate on the 27th with nearly all becoming casualties or prisoners.

Japanese progress was painstaking, even in the face of little conventional resistance. Mountainous jungle blanketed northern Indochina, forcing the IJA to use what few roads and trails led south. All the while they suffered hit and run attacks, sabotage, and targeted killings from Vietnamese irregulars and local European settler militias. There had been some concern in French high command that the locals would not fight hard against fellow Asians, but these fears were not reality, partially due to Japanese atrocities which enraged the local populace. Led by the charismatic and brilliant Ho Chi Minh, local resistance brutalized the IJA, slowing their advance to a crawl. Sarrail reinforced his positions around Hanoi, stockpiled weapons and ammunition, and created killing zones of barbed wire and pre-sited artillery targets. The first bombing raids on Hanoi began in early December and would become a regular occurrence, wearing down the outnumbered French fighters defending the city against superior Japanese aircraft. Unfortunately there was little Sarrail could do besides hold his position and await support from the Métropole.

Paracel Massacre
As the Allies were forced back on the ground, the French delivered a cutting blow to the Imperial Japanese Navy. A fleet consisting of the light carrier Bearn alongside several destroyers, cruisers, and the fast battleships Dunkerque and Strasbourg joined with the Indochinese Fleet in mid December, finally giving the French a naval force capable of mounting an offence. Royal Navy naval patrol aircraft spotted a heavily escorted Japanese convoy in the South China Sea, heading on a course that suggested it was attempting to land at Saigon. The newly dubbed French Pacific Fleet steamed towards the IJN convoy, hoping to catch them at the Paracel islands and outmaneuver them in the narrows and shallows, utilizing the extensive charting ordered by Sarrail before the war.

On December 7th, as night fell, the two fleets closed in on one another. The Japanese were complacent, believing the French would not dare attack in the darkness as indeed they were not the most able night fighters. They were not aware, however, of how well the French knew these waters. Operating in complete darkness, naval aircraft from the Bearn guided the French fleet towards the enemy. Deftly navigating between reefs, sandbars, and islands, the two fast battleships each lead a separate flotilla in a maneuver designed to surprise the enemy. At roughly 2 AM the French flotillas opened up on the unsuspecting Japanese, inflicting panic. An IJN light cruiser was hit in the magazine and went up in flames, capsizing within minutes. The fast moving and firing French battleships gave the impression of a much larger fleet and the Japanese began to withdraw in terror, straight towards a submerged reef. However, they IJN were able night fighters and returned fire, crippling a heavy cruiser and eviscerating several destroyers. Early in the battle, the Japanese light carrier Ryūjō was hit by a spread of torpedoes from the light cruiser Lamotte-Picquet, causing it to list heavily and rendering it unable to launch many aircraft. This allowed the next phase of the French attack to proceed relatively smoothly. Japanese ships began to hit the reefs, not known on their charts. As they struggled to get free, French torpedo and dive bombers descended on the stricken ships. Nevertheless, the IJN's superior firepower was considerable and began to wear on the lighter armoured French, by just after 3 AM the fleet withdraw, leaving enormous destruction in its wake.

This battle would be dubbed the "Paracel Massacre" by the Allied press, despite it being a hard fought victory for the French. It was a victory nonetheless, a decisive one at that. The Japanese invasion fleet was stopped in its tracks. A heavy cruiser, two light cruisers, five destroyers, and roughly a dozen transport ships now lay at the bottom of the ocean, destroyed by the French attack. A battlecruiser was gravely damaged and would be sunk by a Dutch submarine days later while a light carrier would require months in drydock before it was able to sail. Conversely the French lost three obsolete destroyers and a handful of biplanes. These losses were light, but overall damage to the Pacific Fleet was heavy, forcing it into port until early February 1942. This alongside British and German fleet actions put a stop to any more attempts at a naval landing at Saigon. Unfortunately for the Allies, it also left their forces in the South China Sea unable to halt the landings at Malaya that began on the 8th.

Retreat to Hanoi
Victory at the Paracels secured Saigon, allowing Sarrail to move its garrison to Hanoi, leaving some at the small central port of Da Nang. By now the IJA was beginning to break into the flat plains and light forest north of Hanoi. A delaying action at the city of Bac Ninh by a mix of Legionnaires and irregulars was fought from December 20th to the 26th. This allowed all forces in the region to consolidate in and around Hanoi to prepare for the Japanese assault. On New Years Day, Paul-Doumer Bridge, the only bridge from Hanoi across the Red River was destroyed by German Pioneers, symbolizing the beginning of the Defense of Hanoi. Sarrail stated he would stay in the city "until the conclusion."

Defense of Hanoi
With the bridge destroyed, Japanese troops began to take positions for a river crossing assault. Unlike the French who had concealed heavy guns and well stockpiled ammunition, the Japanese suffered a constant lack of heavy artillery shells due to their treacherous supply line which were consistently harassed by guerrillas. This disadvantage was partially mitigated by the overwhelming Japanese aerial advantage as the two squadrons of French fighters were seriously depleted and overstretched. Nevertheless the IJA was hit hard by Allied artillery which had each probable crossing site already zeroed in. The first crossing was attempted on January 4th and was repulsed with staggering losses, failing to make it even halfway over the river. Nevertheless the Japanese persisted, confident in their numerical and material advantage. Two additional assaults were launched at midnight on the 6th and managed to land a few dozen troops before getting swept away by Allied fire, especially the deadly German MG34 machine gun. Frustrated, the Japanese Commander, General Taketa Horishiro, halted the attacks and ordered a stepping up of aerial bombardments. For several days the city was pounded by Japanese bombers as Allied fighters and AA batteries struggled to fend off the onslaught. This effort had a small boost with the arrival of a squadron of German BF109 fighters on the 8th, but air supremacy still firmly belonged to the Japanese. These attacks lead to mounting casualties and rapidly burned through allied shells and machine gun ammunition.

On the 11th a triple prong river crossing backed by air power and artillery surged across the river. Dive bombers dropped 500 lb bombs directly on Allied strong points, inflicting grievous losses and forcing the defenders back. The city was increasingly turned to ruins, much to the anger of the IJA this merely made advancing more difficult. In one of the West's first tastes of brutal urban combat, every block was the site of a bitter struggle. Allied troops inflicted horrific casualties on the Japanese who continued to frontally assault the city in wave after wave. Sarrail continued to rally his multinational troops, often visiting the front-lines to liaise with local commanders. Nevertheless, the frontlines in Hanoi were gradually pushed back as the Japanese advance appeared inexorable.

Assault on Da Nang
As the battle for Hanoi continued its bitter slog, General Horishiro put a plan into action in an attempt to cut off the city. The elite Teishin Shudan paratroop unit was to assault and capture the crucial city of Da Nang. Da Nang was a modestly sized port and served as a hub for railways, roads, and airfields in central Vietnam. Horishiro believed that Sarrail had placed all his regular troops in Hanoi, not knowing he had left a battalion of experienced legionaries alongside the local garrison in Da Nang along with a several heavy guns. Operating at long range, the Japanese airborne force landed on January 12th to intense ground fire. Nevertheless they took a foothold, managing to infiltrate and capture an airfield under the cover of dark. Reinforcements flew in the following day along with crucial supplies and heavy weapons, pushing back French forces. Several counterattacks failed to break through the paratroopers perimeter due to the poor quality of local militia troops. By the 15th roughly 3,600 crack IJA infantry were advancing on Da Nang. Japanese Raiding parties cut communications lines to the north and sabotaged the main railway. However, the heavy guns and Legion infantry helped keep most of the city in French hands.

Closing the Noose, Relief Arrives
Things began to seem dire for the defenders of Hanoi. Now suffering intermittent contact with the rest of the colony, supplies started to run low. Japanese forces made another large push, reaching the city center and capturing the Hanoi Rail Station on the 18th. Flanking movements threatened the Allied left while another river crossing attempted to seal the road south, which would cut off the city completely. Sarrail ordered then Colonel Andrew Marshall to lead his British troops along with several German battalions to counterattack the southern Japanese thrust. Marshall lead a daring night attack backed by synchronized mortar and artillery barrages supported by the Allies' remaining FT-17 tanks throwing the enemy troops into complete disarray and routing them back into the river where they were decimated. Sarrail would later call this the "finest regimental action of the war," Japanese documents found after the war reveal Marshall's attack defeated elements of two infantry divisions.

Despite this success, Allied forces were exhausted and their stockpiles were dwindling. Moral began to noticeably sag as no sign of relief was forthcoming. Due to poor communications, Sarrail did not know the first two divisions of a corps sized relief force had already disembarked in Saigon on the 20th. The divisions traveled up the Indochinese rail network at breakneck speed, leaving several regiments to crush the paratroops before starting towards Hanoi. On January 24th General Horishiro delivered a message to Sarrail saying he was “ready to end the bloodshed in return for your city.” In a now legendary response, Sarrail replied he was “ready to keep the city in return for your blood.” His German troops began to call him "Eisen Mann," or "Iron Man" a name which would be picked up by the Allied and French press, resulting in his enduring moniker, the ''"Iron Man of Hanoi." ''On the 26th German and French fighter and bomber squadron arrived from Europe conducted a ground attack in support of the Hanoi defenders. The next day advanced scouts of the relief force reached the city, confirming that help was coming. For nearly a month the Defenders of Hanoi had held off a force nearly three times their number with limited air support and nearly no outside assistance. As the Allies suffered reverses throughout Pacific, the joint effort at Hanoi served as a morale boosting rallying cry for the embattled alliance.

Counteroffensive and Liberation
Substantial French reinforcements began to arrive on the 28th and started to relieve the tattered defenders who were sent to Saigon for R&R. On the 29th Sarrail was promoted to Général de corps d'armée and placed in charge of the newly created Indochina Command which consisted of all Allied forces in the colony. D.520 and BF 109 fighters tangled in increasing numbers with Japanese Zeroes and Oscars in attempt to achieve Allied air superiority. This succeeded in stopping the nearly uncontested bombings of Allied positions, but the largely inexperienced Franco-German pilots struggled against battle hardened Japanese dogfighters in their nimble aircraft. On the ground the first French counterattack came on the 30th as several infantry regiments backed by R40 tank battalions swept back Japanese troops from the flanks of Hanoi. By February 2nd the IJA occupied a rough semicircle in the city, with the apex centered on the Central Train Station. Limited counterattacks and raids were made in the city itself, but General Sarrail did not wish to attack it directly, fearful of the casualties that would result. Instead a division was landed at Haiphong east of Hanoi and advanced northwest, threatening the Japanese route south to the city. General Horishiro decided to withdraw his forces north to the mountain passes that guarded the approach to southern China and await incoming reinforcements. Starting on February 10th, the IJA staged a fighting retreat, pursued by the French.

The front-line stabilized north of Bac Ninh, with General Horishiro utilizing the heights and natural defences of the Cau River to stall Allied advances. February was dominated by air battles and artillery duels as both sides dug in along the river and reinforced. By the 20th, four French infantry divisions and one German mechanized division faced four Japanese divisions. Allied forces enjoyed a superiority in tanks, heavy and medium guns, and had slightly more aircraft. Despite Horishiro's protests, most of the equipment he requested went to the forces besieging Singapore in an effort to break the deadlock there.

Operation Vengeur
The main allied counteroffensive, dubbed Operation Vengeur, began on March 1st, backed by a large force of mortars, field guns, heavy howitzers, and the largest display of air-power yet seen in the campaign. In the western sector, the German 15th Panzergrenadier division tore through enemy lines and isolated positions on the western heights while simultaneously wheeling to the east towards the IJA center. At roughly the same time, a feint was launched in the center by the French Tonkin Division to draw in Japanese reserves. Sarrail successfully made the Japanese believe his strategy was to push them east towards the sea. IJA reserves furiously attacked the 15th Panzergrenadiers in an effort to stop them from dislodging their defensive line in the west. The Germans held their positions on the newly captured heights and directed brutal artillery fire on the Japanese counterattacking across open ground. By nightfall it appeared most of Horishiro's reserves had been directed towards the Germans who were being forced to fight nearly hand to hand in pitched combat. Finally Sarrail began the third attack, the 27th Mountain Division infiltrated the thinly held eastern heights which had been stripped of men to attack the Germans. French soldiers now appeared all around the bewildered Japanese who quickly broke, conceding the heights.

Horishiro in a fury ordered the eastern heights to be attacked that morning. The fighting was fierce, but Allied firepower and manpower advantages were telling, the position was held. The Japanese positions was precarious and reluctantly they began to withdraw under the cover of night on the 2nd which gave them some relief from Allied fire. On the morning of March 3rd a French motorized regiment managed to break through the retreating enemy lines and wreak havoc in the rear. Sarrail rapidly reinforced the break, turning a fighting retreat into a route. Allied armoured and motorized troops rapidly advanced for several days, before being halted in the mountains by prepared positions and fanatical Japanese air attacks.

By the time Operation Vengeur stopped its advance on March 8th it had been a resounding success. The IJA's defensive line north of Hanoi had been shattered, Allied troops advanced roughly 75 kilometers in five days, taking scores of prisoners as they did so. In several attempts to retake the western and eastern heights, the Japanese had taken horrific casualties, notably losing the bulk of their tanks. Additionally, Allied pilots had finally begun to take control of the air over the Indochina theatre thanks to heavy Japanese aircraft losses from ground-fire during the operation.

The Lang Son Line
The IJA finally halted their retreat in the heights around the city of Lang Son, a few kilometers from China. Here, partially through using forced Vietnamese labour, General Horishiro had constructed a formidable defensive line. Trenches, earthen bunkers, barbed wire, machine gun nests, and belts of mines lay across the peaks surrounding the city. Several probing attacks and aerial reconnaissance gave General Sarrail a full appreciation of the defences he faced. Allied troops took up positions facing the defenders as the generals planned for a way to break through the line.

Numerous unorthodox proposals were put forwards including a paratrooper assault and an amphibious landing up the Chinese coast, but these were ultimately dismissed as too risky. Instead, Sarrail prepared a strategy similar to that of Operation Vengeur. A massive artillery barrage and close air support of quick moving attacks to keep the enemy off balance and confused. Then the Allies would exploit the weakest section of the line for a breakthrough. Nighttime raids and exchanges of artillery fire was all the front was reduced to for several weeks as both sides built up forces.

Then, at roughly 2AM on March 24th rifle and pistol fire was heard coming from an observation post in the far western sector of Allied lines. Communications were attempted but no response was heard on the radio. The fire intensified and at 2:08 a red flare was fired from the post, indicating distress and need for reinforcement. When the commander of a battalion nearby was ordered to assist the post he fired a white flare to signal the post help was coming. This flare illuminated the hillside, suddenly revealing a mass of Japanese soldiers who had infiltrated the jagged and heavily wooded positions during the night. At once they rose up and began to charge the battalion's positions who was now in an utter panic. The fighting was brutal and chaotic with Allied defences thoroughly infiltrated and coordination hampered by confusion and fear. Soon the entire Allied western line held by the Tonkin Division was engulfed in gunfire and screams as commanders tried desperately to get through to isolated units in an attempt to mount a cohesive defence. Pitched battles continued throughout the night and into the morning with the Tonkin Division's commander ordering his units back to try and mitigate casualties.

Japanese units were able to exploit the rough jungle terrain with brutal efficiency, surprising and annihilating smaller units while unhinging larger units. However, Allied air and artillery support gradually forced IJA attacks to a halt in the face of rising casualties by that afternoon. Stragglers from the Tonkin Division continued to reach Allied lines for the next few days, bringing with them horror stories of their harrowing experiences. This threw a wrench into Sarrail's planned attack on the city and its defences. His western sector had been badly mauled and thrown back, making the assault likely to be more costly if he did not take back the lost positions. So a counterattack was organized with Tonkin Division rotated with the 46th Infantry Division which had been in reserve.

On April 2nd the 46th began its methodical advance supported by artillery and aircraft hitting enemy positions with extreme precision as they were of course originally constructed by the Allies. Several ambushed were fended off and heavy machine gun fire suppressed by the first French use of flamethrowers. Steady progress was made, but dense jungle and heavy afternoon rain delayed any advance. Skirmishes continued into the night as Japanese infiltrators attempted to disorganize the 46th's lines. Morning and better weather saw most of the Tonkin Division's positions retaken in the face of determined IJA resistance which suffered from both a lack of manpower and supplies.

Sarrail consolidated his position once more around Lang Son, taking care to make the line more cohesive and keep internal patrols constant to deter any more infiltration. His plan to take the city, too, was altered. Instead of rapid attacks like those undertaken during Operation Vengeur, the 46th Division 's experience showed that in such tough jungle terrain, a methodical and gradual approach similar to that of the Great War was more apt. An enormous number of heavy guns were received by Sarrail alongside a French armoured cavalry division and several squadrons of Franco-German fighters and bombers. As Germany and France began to fully turn their economies to wartime production, the superiority of Allied industry gave them a huge advantage over the Japanese. Pressure was kept up through bombardments, raids, and air attacks through April as Sarrail built up his forces. Operation Mont Blanc, the plan to break though Lang Son, was planned to begin on May 1st.

Operation Mont Blanc
With an ear shattering explosion of guns up and down the line, the operation began in the early morning. Everything from small 60mm mortars to massive 280mm siege guns rained down an accurate barrage on Japanese troops for an hour. IJA infantry was completely bewildered and in shock from the unprecedented ferocity of artillery. The commander of the German 15th Panzergrenadiers later stated that "Sarrail had bought all the fury and horror of Verdun down on those poor soldiers." Indeed Sarrail had served as an infantry officer at Verdun and experienced the awesome power of massed artillery on entrenched positions.

As the main barrage tapered off, smaller guns remained firing to try and suppress Japanese troops as the main advance began. French Char B1 heavy tanks and German Panzer IV mediums moved out alongside infantry, spreading out and using jungle cover. Even with the intense barrage, many Japanese positions were intact and began firing back. Additionally, minefield that were not cleared inflicted losses on the advancing Allies, despite the best efforts of combat engineers. Deeply dug IJA machine gun and artillery strong-points started to pour fire onto Sarrail's troops. Panzer IVs, with their armour at that point being a thin 30mm, took substantial losses from mines and enemy guns. Nevertheless Allied troops closed the distance and began assaulting the main line.

Point blank fire from Char tanks' 75mm howitzers and assault squads with satchel charges and flamethrowers managed to break through at several points. Reinforcements poured in to exploit these breaks and the Japanese front-line began to buckle, finally breaking under intense Allied pressure. Sarrail called a halt to the advance at nightfall to consolidate their gains and prepare for an assault the next day. By now the foremost French positions allowed direct observation of the city and its route back to China. Firefights continued throughout the night, but no major enemy counterattacks were launched. On May 2nd the attack began again, combined infantry-armour attacks supported by artillery and air support. By this time the Japanese air force was seriously outnumbered, allowing Allied Stukas and Breguet 693s to bomb and strafe with little fear of interception. Groundfire, however, was still a threat with many aircraft lost during the operation.

It became apparent to Sarrail that the force he faced was seriously depleted. Although strong resistance was encountered on the first day, on day two of the operation the Japanese seemed to melt away. General Horishiro had lost roughly a third of his troops, close to two thirds of his air force, and nearly the entirety of his tanks. Ammunition and basic supplies began to run low, both due to poor logistics hampered by chronic guerrilla attacks as well as the diversion of materials to fronts in Malaya and the East Indies. Communications were poor and reserves nonexistent, thwarting any attempt to coordinate a defensive, never mind a counterattack, on the second day. Several major peaks were the site of heavier fighter, but generally there was little resistance as the Allies advanced on Lang Son itself. The total liberation of Indochina was close at hand. With his outer defences shattered, Horishiro withdraw what he could to the city, requesting immediate assistance from high command.

The 3rd saw Lang Son surrounded on three sides following some small scale fighting in the woods and hills around it. Sarrail refrained from using heavy artillery or bombers as it was after all a French city with French civilians still living inside it, though not many remained. The most he would allow were mortars with field guns given permission to fire if absolutely necessary. He was criticized for this by some, but stood by his decision. Realizing the hopelessness of his position, General Horishiro ordered the majority of his forces to attempt a breakout towards China on the 4th, he himself staying in the city with a small rearguard. Aerial reconnaissance revealed the breakout and Allied forces attempted to cut the road but were stalled by fanatical, suicidal resistance from Horishiro's rearguard.

This was overcome during the early morning of the 5th and what Japanese troops remained in Lang Son were surrounded in several pockets. That night, with French troops approaching his headquarters, General Taketa Horishiro gave his men permission to surrender, then committed suicide believing he had failed them. Most, however, did not surrender and continued to hold out for one or two more days, many dying in banzai charges. Those who broke out of the city reached China on May 10th. The city was officially declared secure on May 9th. Then, finally, after six months of bitter fighting Indochina was declared liberated on May 12th.

Aftermath
The Indochina Campaign was a decisive victory for the Allies. Japanese troops had failed to subdue the colony, indeed they had failed to take any major cities or ports. This would harshly effect Japanese efforts throughout Southeast Asia over the next year, and ultimately contribute towards their eventual total defeat. Indochina could not be used as a base to support the Japanese campaigns in Burma, Malaya, or the East Indies, all of which were not progressing well by May 1942. Conversely, holding Indochina allowed the Allies a base from which to harass and attack Japanese convoys supporting those theaters. Additionally, it gave them a springboard from which to later liberate southern China and join up with Chinese forces.

Losses during the campaign were mutually heavy, but were harder on the Japanese. IJA causalities were close to twice of those of the Allies and included elite paratroop and marine units which could not easily be replaced. During the failed airborne capture of Da Nang for example nearly 2,000 paratroopers were taken prisoner. Significant losses of aircraft and tanks were also incurred, which was particularly devastating as Japan struggled to assert air superiority in Southeast Asia. In naval actions supporting the campaign, the IJN had lost a number of ships alongside nearly two dozen transport vessels. In terms of personnel, many experienced officers were killed, including General Taketa Horishiro.

Although Horishiro had failed to win victory, he was nonetheless a capable commander. Hamstrung by a lack of supplies, inferior equipment, and for much of the campaign inferior manpower, he managed to mount a defence for four months. His infiltration tactics struck terror into the hearts of Allied troops, while the tenacious defence of Lang Son earned their grudging respect. When Horishiro was discovered dead by French troops he had left a letter to General Sarrail. In it he described his esteem for Sarrail and pleaded for his captured men to be treated fairly despite his failure in leading them. Sarrail hid the letter, gave Horishiro a full military funeral, and suppressed knowledge of his suicide, instead having him be listed as killed in action.