Bắc Lệ ambush The Bac Le ambush ( , Vietnamese : " trận Bắc Lệ " or " trận cầu Quan Âm " ) was a clash during the Tonkin Campaign in June 1884 between Chinese troops of the Guangxi Army and a French column sent to occupy Lang Son and other towns near the Chinese border . The French claimed that their troops had been ambushed by the Chinese . The incident led to the Sino - French War ( August 1884 – April 1885 ) . Background . In late 1883 France and China began to fight an undeclared war in Tonkin . In December 1883 , in the Son Tay Campaign , the French defeated the Black Flag Army and captured the town of Son Tay . In March 1884 , in the Bac Ninh campaign , they defeated China ' s Guangxi Army and captured the strategically important town of Bac Ninh on the Mandarin Road . 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 Thai Nguyen , 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 a Chinese troop withdrawal 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 . 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 . 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 Lang Son and other cities up to the Chinese border . The approach march . In early June 1884 a French column under the command of Lieutenant - Colonel Alphonse Dugenne advanced to occupy the border towns of Lang Son , Cao Bang and That Khe . Dugenne ' s column consisted of a battalion of marine infantry ( " chef de bataillon " Reygasse ) , an artillery battery ( Captain Jourdy ) , a newly recruited company of Tonkinese riflemen , and a small force of " chasseurs d ' Afrique " ( Captain Laperrine ) . Reygasse ' s " marsouins " were veteran soldiers , who had served under the command of Commandant Henri Rivière at the Capture of Nam Dinh ( March 1883 ) , but the Tonkinese riflemen had only been recruited several days earlier , and were of negligible military value . The column needed to take food and rations for 45 days , and the combatants ( 450 Frenchmen and 350 Tonkinese ) were accompanied by 1 , 000 Vietnamese porters , 240 French mule drivers and 200 mules . As the French were advancing through unknown country , Captain Jean - François - Alphonse Lecomte of the topographical service rode with the column to map the route . Lecomte , who served with distinction on General Louis Brière de l ' Isle ' s staff throughout the Sino - French War , would later write a detailed account of the ambush , " Le guet - apens de Bac - Lé " ( Paris , 1890 ) . The column formed at Phu Lang Thuong , the most advanced French post on the Mandarin Road , on 11 June . It set off for Lang Son on 12 June , reaching Phu Xuyen on 13 June , Kep on 14 June and Cau Son on 15 June . The march , under a sweltering summer sun , was gruelling , and on 15 June Dugenne sent Jourdy ' s battery back to Phu Lang Thuong . At the same time he was reinforced by a company of " zéphyrs " from " chef de bataillon " Servière ' s 2nd African Light Infantry Battalion . Recent heavy rain had swollen the Song Thuong river , and the French were unable to use the ford at Cau Son . The column therefore remained at Cau Son for three days while its engineers bridged the Song Thuong , and only resumed its march on 19 June . For the next three days the column pressed on to the northeast , marching parallel to the course of the Thuong river and camping in the open country between Cau Son and the small town of Bac Le . The French now became aware that their march was being observed . Single shots were heard in the distance at regular intervals , and on one occasion French cavalry scouts came under fire . It was not clear whether the attackers were Vietnamese bandits or Chinese soldiers . On the morning of 22 June the French column reached Bac Le . Continuing their march in the afternoon , the French descended once more into the Song Thuong valley and rejoined the river . Dugenne ' s intention was to cross the Song Thuong and continue up the Mandarin Road to Thanh Moy and Lang Son . The river was still swollen , and on the evening of 22 June Dugenne scouted its southern bank for a suitable ford . Chinese soldiers were visible on the other side of the river , and Laperrine ' s troopers covered them with their carbines while a French NCO tested the depth of the river . Neither side opened fire . Believing that he was dealing with stragglers from the Guangxi Army who would not oppose his passage , Dugenne gave orders for a crossing of the Song Thuong the following morning . In fact Dugenne was facing a force of 3 , 100 regular Chinese soldiers of the Guangxi Army under the command of Wan Zhongxuan ( 萬重暄 ) . This force consisted of eight battalions under the command of Huang Yuxian ( 黃玉賢 ) and one battalion under the command of Wang Hongshun ( 王洪順 ) . A further 1 , 500 Chinese troops under the command of Pan Dingxin ( 潘鼎新 ) were camped close by . Most of the Chinese troops were armed with modern rapid - firing Remington rifles . Both commanders were aware of the provisions of the Tientsin Accord , but as a result of the political intrigues aimed at Li Hongzhang they had received no instructions to withdraw from Tonkin . They had instead been ordered by the commander of the Guangxi Army ( a yung - ying regional army ) , Wang Debang ( 王德榜 ) , to hold their positions . Wang Debang had experience serving with General Zuo Zongtang . The ambush . At dawn on 23 June Captain Lecomte crossed the Song Thuong with the column ' s advance guard ( two companies of French infantry , a section of Tonkinese riflemen and a small party of cavalry ) . The crossing was observed by a force of Chinese infantry deployed in a defensive position on a wooded hill 250 metres behind the river . The Chinese allowed the French troops to cross unmolested , but opened fire while the Tonkinese riflemen were crossing . Their shots were high , and it is possible that they were intended to warn rather than to kill . Lecomte reacted immediately to this hostile demonstration , deploying his infantry to flank the Chinese out of their position . The French drove the Chinese from the hill , and Lecomte established a defensive position to shelter the crossing of the rest of the column . By 11 a . m . the entire French column had crossed the Song Thuong . By then an interesting situation had developed at the French advance posts . At 9 a . m . three Chinese envoys came forward with a written message for Dugenne from the Chinese commanders . Lecomte let them through , and an interview took place . Although Dugenne ' s Vietnamese interpreters were unable to grasp some of the subtleties in the Chinese message , they were able to establish that the French were facing regular troops of the Guangxi Army and that the Chinese commanders were aware of their obligations under the Tientsin Accord . The Chinese generals explained that they had received no orders to withdraw , and were consequently obliged to remain in their positions until further notice . They requested Dugenne to send a heliograph message back to Hanoi to seek instructions . In view of the diplomatic significance of the confrontation , Dugenne should have reported the presence of the Chinese force to Hanoi and asked for further instructions . Instead , he informed the Chinese at 3 p . m . that he would continue his march up the Mandarin Road in one hour ' s time . According to Captain Lecomte ( normally a reliable source ) , Dugenne believed that the Chinese would let him pass , and his intention was merely to get his column away from the swollen Song Thuong River and to find a secure camping ground for the night . At 4 p . m . Dugenne resumed his advance . Aware of the potential for a misunderstanding , he gave strict instructions that nobody was to open fire except on his order . For several minutes the French column marched unmolested along a jungle path towards a group of Chinese forts on the cliffs of Nui Dong Nai . Seeing the path opening into a clearing , Dugenne ordered Laperrine ' s cavalry to replace an inexperienced section of Tonkinese riflemen at the front of the column . As the French cavalry spurred their horses forward to move to the front of the column , Chinese infantry in the Nui Dong Nai forts suddenly opened fire on them . Seconds later , Chinese infantry shadowing the march of the French column opened fire on both its flanks . It is not clear whether the Chinese were alarmed by the sudden movement of the French cavalry or ( as the French believed ) they mistook the horsemen for a party of senior officers and deliberately fired on this tempting target . The marine infantry of the French vanguard deployed as best they could and replied to the Chinese fire . Dugenne , who was leading the column ' s main body , ordered a bugler to sound for a ceasefire , but the bugle call had no effect . The Chinese were sounding their own trumpets to bring more of their own men into action , and as it became clear that the battle could not be stopped Dugenne planned his defence . He formed his men into a square , enclosing his vulnerable baggage train , and ordered them to dig trenches . During the late afternoon of 23 March the French successfully repelled repeated Chinese attacks , and were even able to counterattack with some effect . However , the Chinese brought up fresh troops during the night , and occupied positions on the heights of Nui Dong Nai from which they could fire down on the French square . On the morning of June 24 , the Chinese worked their way around the sides of the French square in an attempt to cut the column ' s line of retreat to the Song Thuong . Dugenne made several local counterattacks to take some air around his positions , but it soon became obvious that , with no artillery support , the French would be encircled and annihilated if they remained where they were . At 11 a . m . Dugenne issued orders for a withdrawal to the Song Thuong . Although the column suffered heavy casualties from rifle fire during the withdrawal and was forced to abandon its baggage train , Dugenne successfully fought his way out of the threatened encirclement and extricated his small force . Captain Laperrine , the commander of Dugenne ' s small cavalry contingent , dismounted his troopers so that wounded men could be loaded onto the cavalry horses . The successful evacuation of the wounded was due in no small measure to the coolness with which Laperrine and his " chasseurs d ' Afrique " covered the retreat . Falling back by echelons , the French recrossed the Song Thuong under fire and regrouped on its southern bank . In the afternoon of 24 June the column retreated to Bac Le , followed at a respectful distance by the victorious Chinese , and occupied a defensive position on a high plateau . The relief expedition . Dugenne had heliographed news of the battle back to Hanoi during the night of 23 June , and General Millot , the French commander - in - chief , immediately despatched General François de Négrier and Lieutenant - Colonel Letellier to Dugenne ' s assistance with a substantial relief column assembled from the garrisons of Hanoi and Bac Ninh . He also ordered the 2nd Brigade of the Tonkin Expeditionary Corps to concentrate at Phu Lang Thuong . De Négrier left Hanoi on 24 June with two Turco battalions , two companies of the 143rd Line Battalion and two 80 - millimetre artillery batteries . Travelling upriver aboard a flotilla of steamboats to Phu Lang Thuong and thereafter marching light , de Négrier ' s relief column reached Cau Son on the evening of 25 June . De Négrier joined Dugenne ' s column near Bac Le on the morning of 27 June and made preparations for an immediate counterattack to throw the Chinese back across the Song Thuong . The French scouted the Chinese positions during the afternoon , and de Négrier issued orders for an attack the following morning . However , on the evening of 27 June he received a heliograph message from Millot , ordering him to return to Hanoi at once . The French premier Jules Ferry had decided to lodge a diplomatic protest and demand an explanation from the Chinese government . De Négrier complied with this unwelcome order . During the night of 28 June , under cover of a heavy thunderstorm , he and Dugenne withdrew their respective commands from the Bac Le plateau unnoticed by the Chinese . On the afternoon of 29 June the French reached Cau Son , where the wounded from the Bac Le battle were evacuated back to Phu Lang Thuong by junk . At Phu Lang Thuong the wounded were transferred to the gunboat " Éclair " , which ferried them rapidly back to Hanoi . In early July the exhausted men of Dugenne ' s column returned to Hanoi . De Négrier remained at Phu Lang Thuong with the 2nd Brigade , pressing Millot in vain for orders to attack the Chinese . Casualties . French casualties in the Bac Le Ambush were 22 dead and 70 wounded . Chinese casualties were markedly higher , approximately 300 dead and wounded in total . Millot ' s order of the day . On July 1 , 1884 , General Millot issued the following order of the day to the men of Dugenne ' s column . Significantly , he blamed the engagement near Bac Le on the bad faith of the Chinese and described it as an ambush . Henceforth , the battle became , in French eyes , the ' Bac Le ambush ' . Partis en petit nombre pour occuper , conformément aux ordres du Gouvernement et suivant les conventions de Tien - Tsin , les places frontières du Tonkin et de la Chine , vous avez étés attaqués dans les gorges de Lang - Son par un ennemi déloyal qui s ’ était préparé pour vous attaquer dans un guet - apens . Mais grâce à votre énergie , vous avez déjoué toutes ses ruses , vous avez combattu avec succès à une contre dix et vous avez fait respecter le drapeau et l ’ honneur de nos armes . Quelques baggages abandonnés par les coolies sont restés au pouvoir de l ’ ennemi . Je le proclame bien haut : vous valez les soldats de la première République . Si vous n ’ avez pas vaincu , vous avez rassuré la France par votre courage , votre constance et votre héroïsme . Honneur à vous , soldats , la République vous remercie et inscrira un glorieux fait d ’ armes dans ses annales . Significance . 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 Tientsin 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 Amédée Courbet was ordered to take his Far East Squadron to Fuzhou ( Foochow ) . The negotiations broke down in mid - August and on 23 August 1884 , at the Battle of Fuzhou , Courbet annihilated China ' s Fujian Fleet , inaugurating the nine - month Sino - French War . The defeat of the French forces also resulted in the unsuccessful French attempt to attack and take Taiwan , where the Chinese Huai Army under Liu Mingchuan defeated the French at the Keelung Campaign and Battle of Tamsui .