Sino - French War The Sino - French War ( , , ) , also known as the Tonkin War and Tonquin War , was a limited conflict fought between August 1884 and April 1885 to decide whether France should replace China in control of Tonkin ( northern Vietnam ) . Because the French achieved their war aims , they are usually considered to have won the war . Nevertheless , the Chinese armies performed better than they did in other nineteenth - century foreign wars , and some Chinese and Taiwanese historians dispute this view . Prelude . French interest in northern Vietnam dated from the late 18th century , when the political Catholic priest Pigneau de Behaine recruited French volunteers to fight for Nguyễn Ánh and help begin the Nguyễn Dynasty in an attempt to gain privileges for France and the Roman Catholic Church . In 1858 , France began their colonial campaign and in 1862 annexed several southern provinces of Vietnam to become the colony of Cochinchina , laying the foundations for its later colonial empire in Indochina . French explorers followed the course of the Red River ( Asia ) through northern Vietnam to its source in Yunnan , arousing hopes that an extremely profitable overland trade route could be established with China , bypassing the treaty ports of the Chinese coastal provinces . The main obstacle to the realisation of this dream was the Black Flag Army , a well - organized bandit force under a formidable leader , Liu Yongfu ( Liu Yung - fu , 劉永福 ) , which was levying exorbitant dues on trade on the Red River between Sơn Tây and the town of Lào Cai on the Yunnan border . Henri Rivière ’ s expedition in Tonkin . French intervention in northern Vietnam was precipitated by Commandant Henri Rivière , who was sent with a small French military force to Hanoi at the end of 1881 to investigate Vietnamese complaints against the activities of French merchants . In defiance of the instructions of his superiors , Rivière stormed the citadel of Hanoi on 25 April 1882 . Although Rivière subsequently returned the citadel to Vietnamese control , his recourse to force was greeted with alarm in both Vietnam and China . The Vietnamese government , unable to confront Rivière with its own ramshackle army , enlisted the help of Liu Yongfu , whose well - trained and seasoned Black Flag soldiers were to prove a thorn in the side of the French . The Black Flags had already inflicted one humiliating defeat on a French force commanded by Lieutenant de Vaisseau Francis Garnier in 1873 . Like Rivière in 1882 , Garnier had exceeded his instructions and attempted to intervene militarily in northern Vietnam . Liu Yongfu had been called in by the Vietnamese government and ended a remarkable series of French victories against the Vietnamese by defeating Garnier ' s small French force beneath the walls of Hanoi . Garnier was killed in this battle and the French government later disavowed his expedition . The Vietnamese also bid for Chinese support . Vietnam had long been a vassal state of China , and China agreed to arm and support the Black Flags and to covertly oppose French operations in Tonkin . The Qing court also sent a strong signal to the French that China would not allow Tonkin to fall under French control . In the summer of 1882 , troops of the Chinese Yunnan and Guangxi armies crossed the border into Tonkin , occupying Lạng Sơn , Bắc Ninh , Hung Hoa and other towns . The French minister to China , Frédéric Bourée , was so alarmed by the prospect of war with China that in November and December 1882 he negotiated a deal with the Chinese statesman , Li Hongzhang , to divide Tonkin into French and Chinese spheres of influence . The Vietnamese were not consulted by either party to these negotiations . Rivière was disgusted at the deal cut by Bourée and in early 1883 decided to force the issue . He had recently been sent a battalion of marine infantry from France , giving him just enough men to venture beyond Hanoi . On 27 March 1883 , to secure his line of communications from Hanoi to the coast , Rivière captured the citadel of Nam Định with a force of 520 French soldiers under his personal command . During his absence at Nam Định , the Black Flags and Vietnamese made an attack on Hanoi , but they were repulsed by Chef de Bataillon Berthe de Villers in the Battle of Gia Cuc on 28 March . Rivière was jubilant : ' This will force them to take forward their Tonkin Question ! ' Rivière ' s timing was perfect . He had expected to be cashiered for his capture of Nam Dinh ; instead he found himself the hero of the hour . There had recently been a change of government in France , and the new administration of Jules Ferry was strongly in favour of colonial expansion . It therefore decided to back up Rivière . Ferry and Foreign Minister Paul - Armand Challemel - Lacour denounced Bourée ' s agreement with Li Hongzhang and recalled the hapless French minister . They also made it clear to the Chinese that they were determined to place Tonkin under French protection . In April 1883 , realising that the Vietnamese were incapable of resisting the French effectively , the Chinese civil Mandarin Tang Jingsong ( Tang Ching - sung , 唐景崧 ) persuaded Liu Yongfu to take the field against Rivière with the Black Flag Army . This resulted in a year of Liu Yongfu ' s forces fighting an unconventional war . On 10 May 1883 Liu Yongfu challenged the French to battle in a taunting message widely placarded on the walls of Hanoi . On 19 May Rivière confronted the Black Flags in the Battle of Paper Bridge . The result was a disastrous defeat for the French . Rivière ' s small force ( around 450 men ) attacked a strong Black Flag defensive position near the village of Cầu Giấy , a few miles to the west of Hanoi , known to the French as Paper Bridge ( Pont de Papier ) . After initial successes the French were eventually enveloped on both wings , and were only with difficulty able to regroup and fall back to Hanoi . Rivière , Berthe de Villers and several other senior officers were killed in this action . French intervention in Tonkin . Rivière ' s death produced an angry reaction in France . Reinforcements were rushed to Tonkin , a threatened attack by the Black Flags on Hanoi was averted , and the military situation was stabilised . Protectorate over Tonkin . On 20 August 1883 Admiral Amédée Courbet , who had recently been appointed to the command of the newly formed Tonkin Coasts Naval Division , stormed the forts which guarded the approaches to the Vietnamese capital Huế in the Battle of Thuan An , and forced the Vietnamese government to sign the Treaty of Huế , placing Tonkin under French protection . At the same time the new commander of the Tonkin expeditionary corps , General Bouët , attacked the Black Flag positions on the Day River . Although the French mauled the Black Flag Army in the Battle of Phu Hoai ( 15 August ) and the Battle of Palan ( 1 September ) , they were unable to capture all of Liu Yongfu ' s positions , and in the eyes of the world the battles were tantamount to French defeats . Bouët was widely held to have failed in his mission , and resigned in September 1883 . In the event , severe flooding eventually forced Liu Yongfu to abandon the line of the Day River and fall back to the fortified city of Son Tay , several miles to the west . Confrontation between France and China . The French prepared for a major offensive at the end of the year to annihilate the Black Flags , and tried to persuade China to withdraw its support for Liu Yongfu , while attempting to win the support of the other European powers for the projected offensive . However , negotiations in Shanghai in July 1883 between the French minister Arthur Tricou and Li Hongzhang were terminated by the Qing government on receipt of a naively optimistic assessment by Marquis Zeng Jize , the Chinese minister to Paris , that the French government had no stomach for a full - scale war with China . Jules Ferry and the French foreign minister Paul - Armand Challemel - Lacour met a number of times in the summer and autumn of 1883 with Marquis Zeng in Paris , but these parallel diplomatic discussions also proved abortive . The Chinese stood firm , and refused to withdraw substantial garrisons of Chinese regular troops from Son Tay , Bac Ninh and Lang Son , despite the likelihood that they would be shortly engaged in battle against the French . As war with China seemed increasingly likely , the French persuaded the German government to delay the release of " Dingyuan " and " Zhenyuan " , two modern battleships then being constructed in German shipyards for China ' s Beiyang Fleet . Meanwhile , the French consolidated their hold on the Delta by establishing posts at Quang Yen , Hung Yen and Ninh Binh . The growing tension between France and China gave rise to anti - foreign demonstrations inside China during the autumn of 1883 . The most serious incidents took place in Guangdong province , where attacks were made on the property of European merchants in Guangzhou and on Shamian island . Several European powers , including France , sent gunboats to Guangzhou to protect their nationals . Son Tay and Bac Ninh . The French accepted that an attack on Liu Yongfu would probably result in an undeclared war with China , but calculated that a quick victory in Tonkin would force the Chinese to accept a fait accompli . Command of the Tonkin campaign was entrusted to Admiral Courbet , who attacked Son Tay in December 1883 . The Son Tay Campaign was the fiercest campaign the French had yet fought in Tonkin . Although the Chinese and Vietnamese contingents at Son Tay played little part in the defence , Liu Yongfu ' s Black Flags fought ferociously to hold the city . On 14 December the French assaulted the outer defences of Son Tay at Phu Sa , but were thrown back with heavy casualties . Hoping to exploit Courbet ' s defeat , Liu Yongfu attacked the French lines the same night , but the Black Flag attack also failed disastrously . After resting his troops on 15 December , Courbet again assaulted the defences of Son Tay on the afternoon of 16 December . This time the attack was thoroughly prepared by artillery , and delivered only after the defenders had been worn down . At 5 p . m . a Foreign Legion battalion and a battalion of marine fusiliers captured the western gate of Son Tay and fought their way into the town . Liu Yongfu ' s garrison withdrew to the citadel , and evacuated Son Tay under cover of darkness several hours later . Courbet had achieved his objective , but at considerable cost . French casualties at Son Tay were 83 dead and 320 wounded . The fighting at Son Tay also took a terrible toll of the Black Flags , and in the opinion of some observers broke them once and for all as a serious fighting force . Liu Yongfu felt that he had been deliberately left to bear the brunt of the fighting by his Chinese and Vietnamese allies , and determined never again to expose his troops so openly . In March 1884 the French renewed their offensive under the command of General Charles - Théodore Millot , who took over responsibility for the land campaign from Admiral Courbet after the fall of Son Tay . Reinforcements from France and the African colonies had now raised the strength of the Tonkin Expeditionary Corps to over 10 , 000 men , and Millot organised this force into two brigades . The 1st Brigade was commanded by General Louis Brière de l ' Isle , who had earlier made his reputation as governor of Senegal , and the 2nd Brigade was commanded by the charismatic young Foreign Legion general François de Négrier , who had recently quelled a serious Arab rebellion in Algeria . The French target was Bac Ninh , garrisoned by a strong force of regular Chinese troops of the Guangxi Army . The Bac Ninh campaign was a walkover for the French . Morale in the Chinese army was low , and Liu Yongfu was careful to keep his experienced Black Flags out of danger . Millot bypassed Chinese defences to the southwest of Bac Ninh , and assaulted the city on 12 March from the southeast , with complete success . The Guangxi Army put up a feeble resistance , and the French took the city with ease , capturing large quantities of ammunition and a number of brand new Krupp cannon . The Tientsin Accord and the Treaty of Huế . The defeat at Bac Ninh , coming close on the heels of the fall of Son Tay , strengthened the hand of the moderate element in the Chinese government and temporarily discredited the extremist ' Purist ' party led by Zhang Zhidong , which was agitating for a full - scale war against France . Further French successes in the spring of 1884 , including the Capture of Hung Hoa and Thái Nguyên , convinced the Empress Dowager Cixi that China should come to terms , and an accord was reached between France and China in May . The negotiations took place in Tianjin ( Tientsin ) . Li Hongzhang , the leader of the Chinese moderates , represented China ; and Captain François - Ernest Fournier , commander of the French cruiser " Volta " , represented France . The Tientsin Accord , concluded on 11 May 1884 , provided for Chinese recognition of the French protectorate over Annam and Tonkin and withdrawal of Chinese troops from Tonkin , in return for a comprehensive treaty that would settle details of trade and commerce between France and China and provide for the demarcation of its disputed border with Vietnam . On 6 June the French followed up their accord with China by concluding a fresh Treaty of Hue with the Vietnamese , which established a French protectorate over both Annam and Tonkin and allowed the French to station troops at strategic points in Vietnamese territory and to install residents in the main towns . The signature of the treaty was accompanied by an important symbolic gesture . The seal presented by the emperor of China several decades earlier to the Vietnamese king Gia Long was melted down in the presence of the French and Vietnamese plenipotentiaries , betokening the renunciation by Vietnam of its traditional links with China . Fournier was not a professional diplomat , and the Tientsin Accord contained several loose ends . Crucially , it failed to explicitly state a deadline for the Chinese troop withdrawal from Tonkin . The French asserted that the troop withdrawal was to take place immediately , while the Chinese argued that the withdrawal was contingent upon the conclusion of the comprehensive treaty . In fact , the Chinese stance was an ex post facto rationalisation , designed to justify their unwillingness or inability to put the terms of the accord into effect . The accord was extremely unpopular in China , and provoked an immediate backlash . The war party called for Li Hongzhang ' s impeachment , and his political opponents intrigued to have orders sent to the Chinese troops in Tonkin to hold their positions . The Bac Le ambush . Li Hongzhang hinted to the French that there might be difficulties in enforcing the accord , but nothing specific was said . The French assumed that the Chinese troops would leave Tonkin as agreed , and made preparations for occupying the border towns of Lang Son , Cao Bang and That Ke . In early June 1884 a French column under the command of Lieutenant - Colonel Alphonse Dugenne advanced to occupy Langson . On 23 June , near the small town of Bac Le , the French encountered a strong detachment of the Guangxi Army ensconced in a defensive position behind the Song Thuong River . In view of the diplomatic significance of this discovery , Dugenne should have reported the presence of the Chinese force to Hanoi and waited for further instructions . Instead , he gave the Chinese an ultimatum , and on their refusal to withdraw resumed his advance . The Chinese opened fire on the advancing French , precipitating a two - day battle in which Dugenne ' s column was encircled and seriously mauled . Dugenne eventually fought his way out of the Chinese encirclement and extricated his small force . When news of the ' Bac Le Ambush ' reached Paris , there was fury at what was perceived as blatant Chinese treachery . Ferry ' s government demanded an apology , an indemnity , and the immediate implementation of the terms of the Tianjin Accord . The Chinese government agreed to negotiate , but refused to apologise or pay an indemnity . The mood in France was against compromise , and although negotiations continued throughout July , Admiral Courbet was ordered to take his squadron to Fuzhou ( Foochow ) . He was instructed to prepare to attack the Chinese fleet in the harbour and to destroy the Foochow Navy Yard . Meanwhile , as a preliminary demonstration of what would follow if the Chinese were recalcitrant , Rear Admiral Sébastien Lespès destroyed three Chinese shore batteries in the port of Keelung in northern Formosa ( Taiwan ) by naval bombardment on 5 August . The French put a landing force ashore to occupy Keelung and the nearby coal mines at Pei - tao ( Pa - tou ) , as a ' pledge ' ( " gage " ) to be bargained against a Chinese withdrawal from Tonkin , but the arrival of a large Chinese army under the command of the imperial commissioner Liu Mingchuan ( 劉銘傳 ) forced it to re - embark on 6 August . The Sino - French War , August 1884 to April 1885 . Operations of Admiral Courbet ' s squadron . Fuzhou and the Min River . Negotiations between France and China broke down in mid - August , and on 22 August Courbet was ordered to attack the Chinese fleet at Fuzhou . In the Battle of Fuzhou ( also known as the Battle of the Pagoda Anchorage ) on 23 August 1884 , the French took their revenge for the Bac Le Ambush . In a two - hour engagement watched with professional interest by neutral British and American vessels ( the battle was one of the first occasions on which the spar torpedo was successfully deployed ) , Courbet ' s Far East Squadron annihilated China ' s outclassed Fujian fleet and severely damaged the Foochow Navy Yard ( which , ironically , had been built under the direction of the French administrator Prosper Giquel ) . Nine Chinese ships were sunk in less than an hour , including the corvette " Yangwu " , the flagship of the Fujian fleet . Chinese losses may have amounted to 3 , 000 dead , while French losses were minimal . Courbet then successfully withdrew down the Min River to the open sea , destroying several Chinese shore batteries from behind as he took the French squadron through the Min ' an and Jinpai passes . Riots in Hong Kong . The French attack at Fuzhou effectively ended diplomatic contacts between France and China . Although neither country declared war , the dispute would now be settled on the battlefield . The news of the destruction of the Fujian fleet was greeted by an outbreak of patriotic fervour in China , marred by attacks on foreigners and foreign property . There was considerable sympathy for China in Europe , and the Chinese were able to hire a number of British , German and American army and navy officers as advisers . Patriotic indignation spread to the British colony of Hong Kong . In September 1884 dock workers in Hong Kong refused to repair the French ironclad " La Galissonnière " , which had suffered shell damage in the August naval engagements . The strike collapsed at the end of September , but the dock workers were prevented from resuming their business by other groups of Chinese workers , including longshoremen , sedan chair carriers and rickshawmen . An attempt by the British authorities to protect the dock workers against harassment resulted in serious rioting on 3 October , during which at least one rioter was shot dead and several Sikh constables were injured . The British suspected , with good reason , that the disturbances had been fomented by the Chinese authorities in Guangdong province . French occupation of Keelung . Meanwhile , the French decided to put pressure on China by landing an expeditionary corps in northern Formosa to seize Keelung and Tamsui , redeeming the failure of 6 August and finally winning the ‘ pledge ’ they sought . On 1 October Lieutenant - Colonel Bertaux - Levillain landed at Keelung with a force of 1 , 800 marine infantry , forcing the Chinese to withdraw to strong defensive positions which had been prepared in the surrounding hills . The French force was too small to advance beyond Keelung , and the Pei - tao coal mines remained in Chinese hands . Meanwhile , after an ineffective naval bombardment on 2 October , Admiral Lespès attacked the Chinese defences at Tamsui with 600 sailors from his squadron ' s landing companies on 8 October , and was decisively repulsed by forces under the command of the Fujianese general Sun Kaihua ( 孫開華 ) . As a result of this reverse , French control over Formosa was limited merely to the town of Keelung . This achievement fell far short of what had been hoped for . Blockade of Formosa . Towards the end of 1884 the French were able to enforce a limited blockade of the northern Formosan ports of Keelung and Tamsui and the southern ports of Taiwanfu ( Tainan ) and Takow ( Kaohsiung ) . In early January 1885 the Formosa expeditionary corps , now under the command of Colonel Jacques Duchesne , was substantially reinforced with two battalions of infantry , bringing its total strength to around 4 , 000 men . Meanwhile , drafts from the Hunan Army and Anhui Army had brought the strength of Liu Mingchuan ' s defending army to around 25 , 000 men . Although severely outnumbered , the French captured a number of minor Chinese positions to the southeast of Keelung at the end of January 1885 , but were forced to halt offensive operations in February due to incessant rain . The blockade succeeded because the Chinese northern fleet , commanded by Li Hongzhang , denied help to the southern Chinese fleet , no northern Chinese fleet ships were sent to the battle the French at all . This led the Navy to fail . The most advanced ships were reserved for the northern Chinese fleet by Li Hongzhang , he did not even " consider " using this well equipped fleet to attack the French , since he wanted to make sure it was always under his command . China ' s north and south had rivalries and the government was split into different parties . China did not have a single admiralty in charge of all the Chinese navies , the northern and southern Chinese navies did not cooperate . This was the reason France was able to achieve control over the seas during the war , since they did not fight all of China ' s navy Tianjin ' s northern naval academy also drained southern China of potential sailors , since they enlisted in northern China instead . Shipu Bay , Zhenhai Bay and the rice blockade . Although the Formosa expeditionary corps remained confined in Keelung , the French scored important successes elsewhere in the spring of 1885 . Courbet ' s squadron had been reinforced substantially since the start of the war , and he now had considerably more ships at his disposal than in October 1884 . In early February 1885 part of his squadron left Keelung to head off a threatened attempt by part of the Chinese Nanyang Fleet ( Southern Seas fleet ) to break the French blockade of Formosa . On 11 February Courbet ' s task force met the cruisers " Kaiji " , " Nanchen " and " Nanrui " , three of the most modern ships in the Chinese fleet , near Shipu Bay , accompanied by the frigate " Yuyuan " and the composite sloop " Chengqing " . The Chinese scattered at the French approach , and while the three cruisers successfully made their escape , the French succeeded in trapping " Yuyuan " and " Chengqing " in Shipu Bay . On the night of 14 February , in the Battle of Shipu , the French attacked the Chinese vessels with two torpedo launches . During a brief engagement inside the bay , " Yuyuan " was seriously damaged by torpedoes and " Chengqing " was hit by " Yuyuan " ' s fire . Both ships were subsequently scuttled by the Chinese . The French torpedo launches escaped almost without loss . Courbet followed up this success on 1 March by locating " Kaiji " , " Nanchen " and " Nanrui " , which had taken refuge with four other Chinese warships in Zhenhai Bay , near the port of Ningbo . Courbet considered forcing the Chinese defences , but finally decided to guard the entrance to the bay to keep the enemy vessels bottled up there for the duration of hostilities . A brief and inconclusive skirmish between the French cruiser " Nielly " and the Chinese shore batteries on 1 March enabled the Chinese general Ouyang Lijian ( 歐陽利見 ) , charged with the defence of Ningbo , to claim the so - called ' Battle of Zhenhai ' as a defensive victory . In February 1885 , under diplomatic pressure from China , Britain invoked the provisions of the 1870 Foreign Enlistment Act and closed Hong Kong and other ports in the Far East to French warships . The French government retaliated by ordering Admiral Courbet to implement a ' rice blockade ' of the Yangzi River , hoping to bring the Qing court to terms by provoking serious rice shortages in northern China . The rice blockade severely disrupted the transport of rice by sea from Shanghai and forced the Chinese to carry it overland , but the war ended before the blockade seriously affected China ' s economy . Operations in Tonkin . French victories in the delta . Meanwhile , the French army in Tonkin was also putting severe pressure on the Chinese forces and their Black Flag allies . General Millot , whose health was failing , resigned as general - in - chief of the Tonkin expeditionary corps in early September 1884 and was replaced by General Brière de l ’ Isle , the senior of his two brigade commanders . Brière de l ’ Isle ' s first task was to beat off a major Chinese invasion of the Red River Delta . In late September 1884 large detachments of the Guangxi Army advanced from Langson and probed into the Luc Nam valley , announcing their presence by ambushing the French gunboats " Hache " and " Massue " on 2 October . Brière de l ’ Isle responded immediately , transporting nearly 3 , 000 French soldiers to the Luc Nam valley aboard a flotilla of gunboats and attacking the Chinese detachments before they could concentrate . In the Kep Campaign , ( 2 to 15 October 1884 ) , three French columns under the overall command of General de Négrier fell upon the separated detachments of the Guangxi Army and successively defeated them in engagements at Lam ( 6 October ) , Kép ( 8 October ) and Chũ ( 10 October ) . The second of these battles was marked by bitter close - quarter fighting between French and Chinese troops , and de Négrier ' s soldiers suffered heavy casualties storming the fortified village of Kep . The exasperated victors shot or bayoneted scores of wounded Chinese soldiers after the battle , and reports of French atrocities at Kep shocked public opinion in Europe . In fact , prisoners were rarely taken by either side during the Sino - French War , and the French were equally shocked by the Chinese habit of paying a bounty for severed French heads . In the wake of these French victories the Chinese fell back to Bac Le and Dong Song , and de Négrier established important forward positions at Kep and Chu , which threatened the Guangxi Army ' s base at Lang Son . Chu was only a few miles southwest of the Guangxi Army ' s advanced posts at Dong Song , and on 16 December a strong Chinese raiding detachment ambushed two companies of the Foreign Legion just to the east of Chu , at Ha Ho . The legionnaires fought their way out of the Chinese encirclement , but suffered a number of casualties and had to abandon their dead on the battlefield . De Négrier immediately brought up reinforcements and pursued the Chinese , but the raiders made good their retreat to Dong Song . Shortly after the October engagements against the Guangxi Army , Brière de l ’ Isle took steps to resupply the western outposts of Hung Hoa , Thái Nguyên and Tuyen Quang , which were coming under increasing threat from Liu Yongfu ' s Black Flags and Tang Jingsong ' s Yunnan Army . On 19 November , in the Battle of Yu Oc , a column making for Tuyen Quan under the command of Colonel Jacques Duchesne was ambushed in the Yu Oc gorge by the Black Flags but was able to fight its way through to the beleaguered post . The French also sealed off the eastern Delta from raids by Chinese guerillas based in Guangdong by occupying Tien Yen , Dong Trieu and other strategic points , and by blockading the Cantonese port of Beihai ( Pak - Hoi ) . They also conducted sweeps along the lower course of the Red River to dislodge Annamese guerilla bands from bases close to Hanoi . These operations enabled Brière de l ’ Isle to concentrate the bulk of the Tonkin expeditionary corps around Chu and Kep at the end of 1884 , to advance on Lang Son as soon as the word was given . The Lang Son Campaign . French strategy in Tonkin was the subject of a bitter debate in the Chamber of Deputies in late December 1884 . The army minister General Jean - Baptiste - Marie Campenon argued that the French should consolidate their hold on the Delta . His opponents urged an all - out offensive to throw the Chinese out of northern Tonkin . The debate culminated in Campenon ' s resignation and his replacement as army minister by the hawkish General Jules Louis Lewal , who immediately ordered Brière de l ’ Isle to capture Lang Son . The campaign would be launched from the French forward base at Chu , and on 3 and 4 January 1885 General de Négrier attacked and defeated a substantial detachment of the Guangxi Army that had concentrated around the nearby village of Nui Bop to try to disrupt the French preparations . De Nègrier ' s victory at Nui Bop , won at odds of just under one to ten , was regarded by his fellow - officers as the most spectacular professional triumph of his career . It took the French a month to complete their preparations for the Lang Son Campaign . Finally , on 3 February 1885 , Brière de l ’ Isle began his advance from Chu with a column of just under 7 , 200 troops , accompanied by 4 , 500 coolies . In ten days the column advanced to the outskirts of Lang Son . The troops were burdened with the weight of their provisions and equipment , and had to march through extremely difficult country . They also had to fight fierce actions to overrun stoutly defended Chinese positions , at Tay Hoa ( 4 February ) , Ha Hoa ( 5 February ) and Dong Song ( 6 February ) . After a brief pause for breath at Dong Song , the expeditionary corps pressed on towards Lang Son , fighting further actions at Deo Quao ( 9 February ) , and Pho Vy ( 11 February ) . On 12 February , in a costly but successful battle , the Turcos and marine infantry of Colonel Laurent Giovanninelli ' s 1st Brigade stormed the main Chinese defences at Bac Vie , several kilometres to the south of Lang Son . On 13 February , the French column entered Lang Son which the Chinese abandoned after fighting a token rearguard action at the nearby village of Ky Lua . Siege and relief of Tuyen Quang . The capture of Lang Son allowed substantial French forces to be diverted further west to relieve the small and isolated French garrison in Tuyen Quang , which had been placed under siege in November 1884 by Liu Yongfu ' s Black Flag Army and Tang Jingsong ' s Yunnan Army . The Siege of Tuyen Quang was the most evocative confrontation of the Sino - French War . The Chinese and Black Flags sapped methodically up to the French positions , and in January and February 1885 breached the outer defences with mines and delivered seven separate assaults on the breach . The Tuyen Quang garrison , 400 legionnaires and 200 Tonkinese auxiliaries under the command of " chef de bataillon " Marc - Edmond Dominé , beat off all attempts to storm their positions , but lost over a third of their strength ( 50 dead and 224 wounded ) sustaining a heroic defence against overwhelming odds . By mid - February it was clear that Tuyen Quang would fall unless it was relieved immediately . Leaving de Négrier at Lang Son with the 2nd Brigade , Brière de l ’ Isle personally led Giovanninelli ' s 1st Brigade back to Hanoi , and then upriver to the relief of Tuyen Quang . The brigade , reinforced at Phu Doan on 24 February by a small column from Hung Hoa under the command of Lieutenant - Colonel de Maussion , found the route to Tuyen Quang blocked by a strong Chinese defensive position at Hoa Moc . On 2 March 1885 Giovanninelli attacked the left flank of the Chinese defensive line . The Battle of Hoa Moc was the most fiercely fought action of the war . Two French assaults were decisively repulsed , and although the French eventually stormed the Chinese positions , they suffered very high casualties ( 76 dead and 408 wounded ) . Nevertheless , their costly victory cleared the way to Tuyen Quang . The Yunnan Army and the Black Flags raised the siege and drew off to the west , and the relieving force entered the beleaguered post on 3 March . Brière de l ’ Isle praised the courage of the hard - pressed garrison in a widely quoted order of the day . ‘ Today , you enjoy the admiration of the men who have relieved you at such heavy cost . Tomorrow , all France will applaud you ! ’ The endgame . Bang Bo , Ky Lua and the retreat from Lang Son . Before his departure for Tuyen Quang , Brière de l ' Isle ordered de Négrier to press on from Lang Son towards the Chinese border and expel the battered remnants of the Guangxi Army from Tonkinese soil . After resupplying the 2nd Brigade with food and ammunition , de Négrier defeated the Guangxi Army at the Battle of Dong Dang on 23 February and cleared it from Tonkinese territory . For good measure , the French crossed briefly into Guangxi province and blew up the ' Gate of China ' , an elaborate Chinese customs building on the Tonkin - Guangxi border . They were not strong enough to exploit this victory , however , and the 2nd Brigade returned to Langson at the end of February . By early March , in the wake of the French victories at Hoa Moc and Dong Dang , the military situation in Tonkin had reached a temporary stalemate . Giovanninelli ' s 1st Brigade faced Tang Qingsong ' s Yunnan Army around Hung Hoa and Tuyen Quang , while de Négrier ' s 2nd Brigade at Lang Son faced Pan Dingxin ' s Guangxi Army . Neither Chinese army had any realistic prospect of launching an offensive for several weeks , while the two French brigades that had jointly captured Lang Son in February were not strong enough to inflict a decisive defeat on either Chinese army separately . Meanwhile the French government was pressuring Brière de l ' Isle to send the 2nd Brigade across the border into Guangxi province , in the hope that a threat to Chinese territory would force China to sue for peace . Brière de l ' Isle and de Négrier examined the possibility of a campaign to capture the major Chinese military depot at Longzhou ( Lung - chou , 龍州 ) , 60 kilometres beyond the border , but on 17 March Brière de l ' Isle advised the army ministry in Paris that such an operation was beyond his strength . Substantial French reinforcements reached Tonkin in the middle of March , giving Brière de l ' Isle a brief opportunity to break the stalemate . He moved the bulk of the reinforcements to Hung Hoa to reinforce the 1st Brigade , intending to attack the Yunnan Army and drive it back beyond Yen Bay . While he and Giovanninelli drew up plans for a western offensive , he ordered de Négrier to hold his positions at Lang Son . On 23 and 24 March the 2nd Brigade , only 1 , 500 men strong , fought a fierce action with over 25 , 000 troops of the Guangxi Army entrenched near Zhennanguan on the Chinese border . The Battle of Bang Bo ( named by the French from the Vietnamese pronunciation of Hengpo , a village in the centre of the Chinese position where the fighting was fiercest ) , is normally known as the Battle of Zhennan Pass in China . The French took a number of outworks on 23 March , but failed to take the main Chinese positions on 24 March and were fiercely counterattacked in their turn . Although the French made a fighting withdrawal and prevented the Chinese from piercing their line , casualties in the 2nd Brigade were relatively heavy ( 70 dead and 188 wounded ) and there were ominous scenes of disorder as the defeated French regrouped after the battle . As the brigade ' s morale was precarious and ammunition was running short , de Négrier decided to fall back to Lang Son . The coolies abandoned the French and the French also had supply issues . The Chinese also outnumbered the French . The Chinese advanced slowly in pursuit , and on 28 March de Négrier fought a battle at Ky Lua in defence of Lang Son . Rested , recovered and fighting behind breastworks , the French successfully held their positions and inflicted crippling casualties on the Guangxi Army . French casualties at Ky Lua were 7 men killed and 38 wounded . The Chinese left 1 , 200 corpses on the battlefield , and a further 6 , 000 Chinese soldiers may have been wounded . The battle of Ky Lua gave a grim foretaste of the horrors of warfare on the Western Front thirty years later . Towards the end of the battle de Négrier was seriously wounded in the chest while scouting the Chinese positions . He was forced to hand over command to his senior regimental commander , Lieutenant - Colonel Paul - Gustave Herbinger . Herbinger was a noted military theoretician who had won a respectable battlefield reputation during the Franco - Prussian War , but was quite out of his depth as a field commander in Tonkin . Several French officers had already commented scathingly on his performance during the Lang Son campaign and at Bang Bo , where he had badly bungled an attack on the Chinese positions . Upon assuming command of the brigade , Herbinger panicked . Despite the evidence that the Chinese had been decisively defeated and were streaming back in disarray towards the Chinese frontier , he convinced himself that they were preparing to encircle Lang Son and cut his supply line . Disregarding the appalled protests of some of his officers , he ordered the 2nd Brigade to abandon Lang Son on the evening of 28 March and retreat to Chu . The Retreat from Lang Son was conducted without loss and with little interference from the Chinese , but Herbinger set an unnecessarily punishing pace and abandoned considerable quantities of food , ammunition and equipment . When the 2nd Brigade eventually rallied at Chu , its soldiers were exhausted and demoralised . Meanwhile the Chinese general ( 潘鼎新 ) , informed by sympathisers in Lang Son that the French were in full retreat , promptly turned his battered army around and reoccupied Lang Son on 30 March . The Chinese were in no condition to pursue the French to Chu , and contented themselves with a limited advance to Dong Song . The retreat was seen as a Chinese victory . There was also bad news for the French from the western front . On 23 March , in the Battle of Phu Lam Tao , a force of Chinese regulars and Black Flags surprised and routed a French zouave battalion that had been ordered to scout positions around Hung Hoa in preparation for Giovanninelli ' s projected offensive against the Yunnan Army . Collapse of Ferry ' s government . Neither reverse was serious , but in the light of Herbinger ' s alarming reports Brière de l ’ Isle believed the situation to be much worse than it was , and sent an extremely pessimistic telegram back to Paris on the evening of 28 March . The political effect of this telegram was momentous . Ferry ' s immediate reaction was to reinforce the army in Tonkin , and indeed Brière de l ’ Isle quickly revised his estimate of the situation and advised the government that the front could soon be stabilised . However , his second thoughts came too late . When his first telegram was made public in Paris there was an uproar in the Chamber of Deputies . A motion of no confidence was tabled , and Ferry ' s government fell on 30 March . The ' Tonkin Affair ' , as this humiliating blow to French policy in Tonkin was immediately dubbed , effectively ended Ferry ' s distinguished career in French politics . He would never again become premier , and his political influence during the rest of his career would be severely limited . His successor , Henri Brisson , promptly concluded peace with China . The Chinese government agreed to implement the Tientsin Accord ( implicitly recognising the French protectorate over Tonkin ) , and the French government dropped its demand for an indemnity for the Bac Le Ambush . A peace protocol ending hostilities was signed on 4 April , and a substantive peace treaty was signed on 9 June at Tianjin by Li Hongzhang and the French minister Jules Patenôtre . China ' s fear of Japan . An important factor in China ' s decision to make peace was fear of Japanese expansionism . Japan had taken advantage of China ' s distraction with France to intrigue in the Chinese protectorate state of Korea . In December 1884 the Japanese sponsored a coup attempt in Seoul which was crushed by the intervention of Chinese troops under the command of Yuan Shikai . The so - called ' Gapsin Coup ' brought Japan and China to the brink of war , and thereafter the Qing court considered that the Japanese were a greater threat to China than the French . Fear of Japan trumped fear of France , and in January 1885 the Empress Dowager directed her ministers to seek an honourable peace with France . Secret talks between the French and Chinese were held in Paris in February and March 1885 , and the fall of Ferry ' s ministry removed the last remaining obstacles to a peace . Final engagements . Ironically , while the war was being decided on the battlefields of Tonkin and in Paris , the Formosa expeditionary corps won two spectacular victories in March 1885 . In a series of actions fought between 4 and 7 March Colonel Duchesne broke the Chinese encirclement of Keelung with a flank attack delivered against the east of the Chinese line , capturing the key position of La Table and forcing the Chinese to withdraw behind the Keelung River . Duchesne ' s victory sparked a brief panic in Taipei , but the French were not strong enough to advance beyond their bridgehead . The Keelung Campaign now reached a point of equilibrium . The French were holding a virtually impregnable defensive perimeter around Keelung but could not exploit their success , while Liu Mingchuan ' s army remained in presence just beyond their advanced positions . However , the French had one card left to play . Duchesne ' s victory enabled Admiral Courbet to detach a marine infantry battalion from the Keelung garrison to capture the Pescadores Islands in late March . Strategically , the Pescadores Campaign was an important victory , which would have prevented the Chinese from further reinforcing their army in Formosa , but it came too late to affect the outcome of the war . Future French operations were cancelled on the news of Lieutenant - Colonel Herbinger ' s retreat from Lang Son on 28 March , and Courbet was on the point of evacuating Keelung to reinforce the Tonkin expeditionary corps , leaving only a minimum garrison at Makung in the Pescadores , when hostilities were ended in April by the conclusion of preliminaries of peace . The news of the peace protocol of 4 April did not reach the French and Chinese forces in Tonkin for several days , and the final engagement of the Sino - French War took place on 14 April 1885 at Kép , where the French beat off a half - hearted Chinese attack on their positions . Meanwhile Brière de l ’ Isle had reinforced the key French posts at Hung Hoa and Chu , and when hostilities ended in the third fortnight of April the French were standing firm against both the Guangxi and Yunnan armies . Although Brière de l ’ Isle was planning to attack the Yunnan Army at Phu Lam Tao to avenge the defeat of 23 March , many French officers doubted whether this offensive would have succeeded . At the same time , the Chinese armies had no prospect whatsoever of driving the French from Hung Hoa or Chu . Militarily , the war in Tonkin ended in a stalemate . The peace protocol of 4 April required the Chinese to withdraw their armies from Tonkin , and the French continued to occupy Keelung and the Pescadores for several months after the end of hostilities , as a surety for Chinese good faith . Admiral Courbet fell seriously ill during this occupation , and on 11 June died aboard his flagship " Bayard " in Makung harbour . Meanwhile the Chinese punctiliously observed the terms of the peace settlement , and by the end of June 1885 both the Yunnan and Guangxi armies had evacuated Tonkin . Liu Yongfu ' s Black Flag Army also withdrew from Tonkinese territory . French attempts to secure an alliance with Japan . The French were well aware of China ' s sensitivities regarding Japan , and as early as June 1883 , in the wake of Rivière ' s death at Paper Bridge , began angling for an alliance with Japan to offset their precarious military position in Tonkin . The French foreign minister Paul Challemel - Lacour believed that France " ought not to disdain the support which , at an appropriate moment , the attitude of Japan would be able to supply to our actions " . In order to court the Japanese government , France offered to support , against British opposition , Japan ' s pleas for revision of the unequal treaties of the Bakumatsu era , which provided extra - territoriality and advantageous tariffs to foreigners . Japan welcomed the offer of French support , but was reluctant to be drawn into a military alliance . Japan was in effect quite worried of the military might China represented , at least on paper , at that time . As the situation in Annam deteriorated however , France was even more anxious of obtaining Japanese help . After French difficulties in Taiwan , new attempts at negotiating an alliance were made with the Minister General Campenon meeting with General Miura Gorō , but Gorō remained ambiguous , encouraging France to continue to support Japan ' s drive for Treaty revision . Hopes for an alliance were reawakened in December 1884 when a clash occurred between China and Japan in Korea , when Japan supported the Gapsin coup d ' état by Kim Okgyun against the pro - Chinese Korean government , prompting Jules Ferry to request the French ambassador in Japan Sienkiewicz to approach the Japanese government with an offer . Sienkiewicz however remained extremely negative to the point of refraining from communicating Ferry ' s proposal . French interest faded in 1885 as the campaign in Tonkin progressed , while , on the contrary Japanese interest increased as the Japanese government and public opinion started to favour open conflict with China . The Sino - French war ended however without an alliance coming to fruition . Aftermath . The peace treaty of June 1885 gave the French most of what they wanted . They were obliged to evacuate Formosa and the Pescadores ( which Courbet had wanted to retain as a French counterweight to the British colony of Hong Kong ) , but the Chinese withdrawal from Tonkin left the way clear for them to reoccupy Lang Son and to advance up the Red River to Lao Cai on the Yunnan - Tonkin border . In the years that followed the French crushed a vigorous Vietnamese resistance movement and consolidated their hold on Annam and Tonkin . In 1887 , Cochinchina , Annam and Tonkin ( the territories which comprise the modern state of Vietnam ) and Cambodia were incorporated into French Indochina . They were joined a few years later by Laos , ceded to France by Siam at the conclusion of the Franco - Siamese War of 1893 . France had to drop demands for an indemnity from China . Domestically , the unsatisfactory conclusion to the Sino - French War dampened enthusiasm for colonial conquest . The war had already claimed Ferry ' s scalp , and his successor Henri Brisson also resigned in the wake of the acrimonious ' Tonkin Debate ' of December 1885 , in which Clemenceau and other opponents of colonial expansion nearly succeeded in securing a French withdrawal from Tonkin . In the end , the Chamber voted the 1886 credits to support the Tonkin expeditionary corps by 274 votes to 270 . If only three votes had gone the other way , the French would have left Tonkin . As Thomazi would later write , ' France gained Indochina very much against its own wishes . ' The reverberations of the Tonkin Affair tarnished the reputation of the proponents of French colonial expansion generally , and delayed the realisation of other French colonial projects , including the conquest of Madagascar . It was not until the early 1890s that domestic political support for colonial expansion revived in France . As far as China was concerned , the war hastened the emergence of a strong nationalist movement , and was a significant step in the decline of the Qing empire . The loss of the Fujian fleet on 23 August 1884 was considered particularly humiliating . The Chinese strategy also demonstrated the flaws in the late Qing national defence system of independent regional armies and fleets . The military and naval commanders in the south received no assistance from Li Hongzhang ' s Northern Seas ( Beiyang ) fleet , based in the Gulf of Zhili , and only token assistance from the Southern Seas ( Nanyang ) fleet at Shanghai . The excuse given , that these forces were needed to deter a Japanese penetration of Korea , was not convincing . The truth was , that having built up a respectable steam navy at considerable expense , the Chinese were reluctant to hazard it in battle , even though concentrating their forces would have given them the best chance of challenging France ' s local naval superiority . The Empress Dowager and her advisers responded in October 1885 by establishing a Navy Yamen on the model of the admiralties of the European powers , to provide unified direction of naval policy . The benefits of this reform were largely nullified by corruption , and although China acquired a number of modern ships in the decade after the Sino - French War the Chinese navies remained handicapped by incompetent leadership . The bulk of China ' s steamship fleet was destroyed or captured in the Sino - Japanese War ( 1894 – 1895 ) , and for decades thereafter China ceased to be a naval power of any importance .