Yên Bái mutiny The Yên Báy mutiny was an uprising of Vietnamese soldiers in the French colonial army on 10 February 1930 in collaboration with civilian supporters who were members of the Việt Nam Quốc Dân Đảng ( VNQDD , the Vietnamese Nationalist Party ) . The attack was the largest disturbance against the colonisation of Vietnam since the Can Vuong monarchist movement of the late 19th century . The aim of the revolt was to inspire a wider uprising among the general populace in an attempt to overthrow the colonial regime and establish independence . The VNQDD had previously attempted to engage in clandestine activities to undermine French rule , but increasing French scrutiny on their activities led to their leadership group taking the risk of staging a large scale military attack in the Red River Delta in northern Vietnam . Shortly after midnight on 10 February , about 50 Vietnamese soldiers ( Lính tập or " Tirailleurs indochinois " ) of the 4th Regiment of Tonkinese Rifles within the Yen Bay garrison turned on their French officers with assistance from about sixty civilian VNQDD members who invaded the camp from the outside . The mutiny failed within 24 hours when the majority of the Vietnamese soldiers in the garrison refused to participate and remained loyal to the colonial army . Further sporadic attacks occurred across the Delta region , with little impact . French retribution to the attack was swift and decisive . The main leaders of the VNQDD were arrested , tried and put to death , effectively ending the military threat of what was previously the leading Vietnamese nationalist revolutionary organisation . The civilian judicial crackdown was followed by sweeping reforms with respect to the using of Vietnamese soldiers in the French colonial army . French trust in the Vietnamese soldiers ' loyalty as colonised subjects who were simultaneously enforcers of colonial order had never been high , and the mutiny resulted in increased safeguards against Vietnamese soldiers in an attempt to prevent future incidents . Around 80 % of the Vietnamese soldiers in Tonkin were transferred to other districts in order to disrupt any secret plots that may have been in progress , and some soldiers who had returned from foreign service were discharged in the fear that their overseas experiences made them less likely to accept colonial subjugation . The internal reform saw the rules for expelling Vietnamese soldiers from the army were liberalised and an inquiry into military intelligence resulted in closer cooperation between military intelligence and their French colonial civilian counterparts , while French officers were ordered to improve their Vietnamese language skills . The French authorities decreed that the proportion of ethnic Vietnamese soldiers was too high and reduced the proportion of Vietnamese by replacing them with European , Cambodian , Lao and ethnic minority Montagnard people . Background and planning . Vietnam had gradually become a French colony between 1859 and 1883 . The first phase started in 1859 , when French and Spanish forces began an invasion of southern Vietnam , leading to the ceding of three southern provinces to form the colony of Cochinchina under the Treaty of Saigon in 1864 . In 1867 , the French seized three further provinces and by 1883 , the process was complete , when northern and central Vietnam were conquered and made into the French protectorates of Tonkin and Annam and incorporated into French Indochina . Initially , military resistance to French rule came through the Can Vuong movement led by Ton That Thuyet and Phan Dinh Phung , which sought to install the boy Emperor Ham Nghi at the head of an independent nation . However , with the death of Phung in 1895 , military opposition effectively ended . The only other notable incidents after this came in 1917 with the Thai Nguyen rebellion . The lack of militant activity changed in the late 1920s with the formation of the VNQDD , or Vietnamese Nationalist Party . The party began to generate attention among French colonial authorities and was blamed for the assassination of Bazin on 9 February 1929 , a French labour recruiter despised among the populace , leading to a heavy French crackdown . The French purges caused considerable detriment to the independence movement in general and the VNQDD in particular . Nearly 1000 VNQDD members were arrested ; the demolition of many of the Party ' s facilities ensued . The VNQDD decided to abandon its clandestine philosophy and engage in open attacks against the French , hoping to foment a general uprising among the people . Since the VNQDD was only strong in the northern areas of Vietnam , the attacks were to be staged in the Red River Delta , and the garrison at Yen Bay was identified as a key point . The French authorities used Vietnamese soldiers and VNQDD members were among the garrison at Yen Bay ; they engaged in cajoling their colleagues with revolutionary rhetoric . On January 28 , 1930 , a final planning meeting was held in the village of Vong La in Phu Tho province . The VNQDD leader Nguyen Thai Hoc declared that the situation was reaching desperation , and asserted that if the party did not act soon , they would be scattered by French police . Hoc built up enthusiasm for the revolt , and those who were reluctant to carry through were coerced into complying . The uprising was set for the night of February 9 and the small hours of the following day . Hoc was to command forces in the lower Red River Delta near the city of Haiphong , Nguyen Khac Nhu was assigned the upper delta around Yen Bay and Pho Duc Chinh was to lead an attack on the military post at Son Tay . Nguyen The Nghiep , who had split with the main body of the VNQDD , led a group who was now across the Chinese border in Yunnan province . He said that he had the support of local soldiers at the Lao Cay garrison and would launch attacks on French border posts , so exiled VNQDD members could re - enter Vietnam and join the uprising . The uprisings were supposed to be simultaneous , but Hoc sent a last minute order to Nhu to postpone action until February 15 . The messenger was arrested by the French and Nhu was unaware of the change in schedule . Yen Bay was a military post comprising more than 600 troops in four companies of infantry . These were commanded by twenty French officers and non - commissioned officers . VNQDD members had been espousing revolutionary sentiment in the area for several months and there was considerable tension in the town leading up to the planned mutiny . The nearby village of Son Duong in Phu Tho was a hotbed of preparations , as many of the bombs used by the VNQDD were manufactured there . More than 100 bombs were made at the home of Nguyen Bac Dang , who also led the recruitment of villagers in his area . It was there that Nhu prepared a command post to coordinate what would be the centrepiece of the attack , the assaults against Yen Bay and Phu Tho . Some VNQDD members , villagers from Son Duong and other settlements in the district of Lam Thao , both male and female , had begun to arrive in Yen Bay with weapons in their baggage . They travelled to the garrison town by train on the pretence of going on a pilgrimage to a noted temple . They carried bombs , scimitars , and insignia , which they hid under religious material , such as incense and fruit and flowers that were to be offered at the altar . The group split into three and disembarked at three different stations in order to avoid raising the suspicion of the police . They were then led to hideouts by those Vietnamese soldiers in the colonial army who were in league with them . On 9 February , the evening before the attacks , back in Son Duong , a large contingent of rebels made their final preparations before heading into battle . They met at three points ; the homes of Bang and the local Confucian scholar , and in the fields . They then joined together for a final meeting before Nhu divided the combined forces in two groups . Nhu led one towards a barracks in Hung Hoa , while the other would attack the town facilities in the district capital of Lam Thao . Some members of the rebels wore khaki uniforms and they departed for their objective after midnight . Nhu was armed with the pistol , while the others were each given a scimitar and two bombs . The groups traversed rivers on boats and arrived outside their attack points , where they were to synchronised their assaults by sending a light signal . The local French commander at Yen Bay had been warned of suspicious circumstances , and although he gave them no credence , he did implement minor precautions . At nightfall , the VNQDD conspirators in Yen Bay held a final meeting on a nearby hill . They wore red and gold silk headbands . The red stood for revolution and the gold represented the Vietnamese people . They donned red armbands with the words " Vietnamese Revolutionary Forces " . Around forty attended and some wanted to back down , but the remainder threatened to have them shot . Attack . At around 1 : 30 a . m . on Monday , 10 February 1930 , approximately 50 troops belonging to the Second Battalion of the Fourth Regiment of Tonkinese Rifles ( " Régiment de Tirailleurs Tonkinois " ) , stationed at Yen Bay , reinforced by around 60 civilian members of the VNQDD , attacked their 29 French officers and warrant officers . The plan was for the rebels to split into three groups . One group was to infiltrate the infantry barracks , kill French NCOs in their beds and raise support amongst the Vietnamese troops ; a second , which was to include the external VNQDD members , was to fight its way into the post headquarters , while the third group would enter the officers ' quarters . The longer term goal was to capture the barracks , secure the city , set up anti - aircraft guns in the hills and create a strong point around the railway station . They were to dig trenches around it to defend it from incoming colonial forces . The Frenchmen were caught off guard and five were killed , with three seriously wounded . The mutineers managed to win over a few more tirailleurs from the 5th and 6th companies of the battalion , and even managed to raise the flag of the VNQDD on top of one of the buildings . They managed to capture the armoury and proclaimed victory . The leaders of the uprising sent a patrol into the centre of the town to exhort the populace to join the insurrection , falsely claiming that they had already eliminated the entire French officer corps . About two hours later , it became apparent that the badly coordinated uprising had failed , as the remaining 550 native soldiers refused to participate in the mutiny , instead helping to quell the rebellion . Some went into the town to protect French civilians and office buildings from attack . Three Vietnamese sergeants were subsequently awarded the " Médaille militaire " for their role in the suppression of the mutiny , while six other tirailleurs received the " Croix de Guerre " . The attack initially generated confusion among the French administration . It was widely reported by the French media in Vietnam and Europe that the Indochinese Communist Party had organised the uprising . Due to the failure of their attempt to take control of the barracks , the VNQDD leaders did not get around to seizing the train station and reinforcing it . They also forgot to cut the telegraph lines , allowing the colonial forces to send a message requesting air support . One reason given to explain the failure of the bulk of the garrison to support the rebels was that a local VNQDD leader inside the garrison , Quang Can , had fallen ill in the lead - up and was sent to a hospital in Hanoi . When he heard of the failed uprising , he committed suicide . In addition , the insurrectionists had failed to liquidate the " Garde indigène " ( native gendarmerie ) post of Yen Bay town and were unable to convince the frightened civilian population to join them in a general revolt . At 07 : 30 , a counterattack by tirailleurs of the 8th company of the battalion led by their French commander , backed by a single aircraft , scattered the mutineers ; two hours later , order was re - established in Yen Bay . On the same evening , the two VNQDD insurrectionary attempts in the Son Duong sector also failed . When Nhu saw the light flashing from Lam Thao , he ordered his men — numbering around 40 — to enter Hung Hoa and head for the barracks , to raid the " Garde indigène " post . Nhu ' s men traversed the streets and avoided passing the French administrative offices and arrived at the military complex , shouting at the Vietnamese sentries to open the doors and join the revolt . One of the VNQDD militants carried a banner saying " Revolutionary Armed Forces : Every Sacrifice for the Liberation of the Fatherland and the Vietnamese People " . They had banked on their countrymen joining them , but instead were met with gunfire . The VNQDD responded by throwing bombs over the walls and setting fire to a side door . They then forced their way in and focused their attack on the residence of the commanding officer , but he managed to escape . Three of the men penetrated the officer ' s compounds to mount a search . The colonial forces were vastly stronger and easily repelled the VNQDD group , who retreated and headed towards the river . However , their three comrades were in the compound searching for the commanding officer and did not hear the signal to retreat . Nevertheless they were able to escape after the colonial troops had already dispersed their VNQDD colleagues . The French captured three other men and 17 unused bombs . It appeared that the Vietnamese soldiers and " Garde indigène " gendarmes comprising the Hung Hoa garrison had received prior warning of the insurrection . The VNQDD members had done propaganda work in trying to cultivate the Hung Hoa tirailleurs in the past and were confident of being able to sway them . Possibly wary of the loyalty of the locally recruited " tirailleurs " and " gardes " , French officials had brought in 50 troops from another area on the eve of the uprising . Nhu then decided that his men would go to Lam Tho to reinforce their colleagues . On the way , they stopped at the nearby town of Kinh Khe , where the instructor , Nguyen Quang Kinh , and one of his two wives were slain by VNQDD members in an apparent revenge killing . Kinh had previously been affiliated with the VNQDD , whose members took him away . His wife had tried to follow him , so the VNQDD captured her as well . French intelligence reports speculated that Kinh had been killed because he would not join his former colleagues . Nhu then led his men through Lam Tho . The plan was that they would help to consolidate the other unit ' s control on the town until the afternoon . They were hopeful that the attack in Yen Bay would have been successfully completed by then , and that the mutineers and people of Yen Bay would come to Lam Tho and stage their forces before attacking the barracks at Phu Tho . However , they were not fast enough . Earlier in the night , the NVQDD group at Lam Thao had managed to destroy the " Garde indigène " post in Lam Thao and the VNQDD briefly seized control of the district seat . They had disarmed the Vietnamese personnel of the " Garde indigène " detachment in the town and the district chief fled , so the nationalists were only able to burn down his quarters . A young VNQDD member had rallied the towns population by propounding the plans of the VNQDD , and the population in the surrounding areas responded by entering the town shouting nationalist slogans and offering to either volunteer to join the uprising or donate food supplies . The VNQDD flag was raised over the town and a proclamation of victory was read out . At sunrise , a newly arrived " Garde indigène " unit inflicted heavy losses on the insurgent group , mortally wounding Nhu , one of the main leaders of the VNQDD . Nhu attempted to commit suicide , finally succeeding on the third attempt . Many of the rebels were captured and the remainder retreated . The French engaged in punitive raids into Son Duong , burning down 69 homes , forcing the villages to pay extra taxes and perform corvee labour to rebuild the destroyed French property in Lam Thao . Aware of what had happened in the upper delta region , Chinh abandoned plans for an attack on the Son Tay garrison and fled , but he was captured a few days later by French authorities . The French imposed a curfew on Hanoi , the capital of northern Vietnam for 12 days . French troops were sent to Son Tay and Phu Tho where attacks by the VNQDD had been planned , and reinforcements were sent to Tuyen Quang , Nam Dinh and Hai Duong as well . Garrisons that consisted entirely of Vietnamese were reinforced with French soldiers . A few further violent incidents occurred until February 22 , when Governor - General of French Indochina Pierre Pasquier declared that the insurrection had been defeated . On February 10 , a policeman was injured by a VNQDD member at a checkpoint in Hanoi ; at night , arts students pelted government buildings with bombs . The buildings were targeted because they symbolised what the students regarded as the colonial state ' s repressive power . On the night of February 15 and the early morning of February 16 , the nearby villages of Phu Duc in Thai Binh province and Vinh Bao in Hai Duong province were seized for a few hours by the leader of the VNQDD , Nguyen Thai Hoc , and his remaining forces . In the first case , the VNQDD fighters disguised themselves and colonial troops and managed to trick their opponents , before seizing the military post in the town . In the process , they wounded three guards and disarmed the post . In the second village , the local mandarin of the French colonial government , Tri Huyen , was murdered . After being driven out , the VNQDD fled to the village of Co Am . On February 16 , French warplanes responded by bombarding the settlement . It was the first time that air power had been used in Indochina . Five wooden Potez 35 biplanes dropped 60 10 kg bombs on the village and raked machine - gun fire indiscriminately , killing 200 , mostly civilians . On the same day , Tonkin ' s Resident Superior René Robin , ordered a mopping - up operation involving two hundred " Gardes indigènes " , eight French commanders and two Sûreté inspectors . The insurrection was officially declared over on February 22 , after Hoc and his lieutenants , Pho Duc Chinh and Nguyen Thanh Loi , were apprehended while trying to flee into China . Robin told his officials to publicise the punitive bombing of the village in order to intimidate and dissuade other settlements from supporting the VNQDD . French reaction . Neither the mutiny nor the popular uprising came entirely as a surprise to the French authorities . The colonial government ' s first large scale crackdown on the VNQDD in 1929 had substantially damaged the party , which had modelled itself on the Chinese Kuomintang of Chiang Kai - shek . The crackdown also had the effect of increasing the violent tendencies within what remained of the VNQDD . Its remaining leadership was now willing to intensify preparations for a violent overthrow of colonial rule to create an independent Vietnamese republic . Most of the party ' s leadership ranks , but not its lower - ranking members and affiliates , seem to have concluded that they were too weak and too closely spied on by the Sûreté to have a meaningful chance of success . At the most optimistic , they could hope to trigger a spontaneous uprising ; at the worst , the subsequent French reprisals would transform them into anti - colonial martyrs . Finally , there was disagreement or a communication problem over the timing of the insurrection : after Hoc had ordered the postponement of the mutiny , Nhu still proceeded . Judicial measures . One of the first responses taken in the aftermath of Yen Bay mutiny was the " purification of units and the sending of those contaminated into detention or into isolated disciplinary units " . This consisted of an internal army purge organised by military authorities , and the prosecution of civilian and military participants in the mutiny and in the VNQDD uprising at large by the relevant civilian authorities . The judicial action occurred through the Criminal Commission of Tonkin , created by Governor General Pasquier on February 12 , and presided over by Jules Bride . It convened five times in four different places during 1930 . It prosecuted 547 individuals , soldiers and civilians alike , and handed down 80 death sentences ( not all of which were enacted ) , 102 life sentences of forced labour , 243 deportations , 37 sentences of forced labour for 20 years , six shorter sentences of forced labour , two lifelong detentions , and one term detention for 20 years . There were 18 acquittals , and 58 accused individuals could not be prosecuted due to lack of evidence . 16 In addition to the Criminal Commission , provincial tribunals were also involved in the legal procedures . The largest number of death penalties were handed down by the first Criminal Commission , which had convened at Yen Bay to try those implicated in the mutiny and nearby insurrections . Among the 87 people found guilty at Yen Bay , 46 were servicemen . Some of them defended themselves on the reasoning that they had been " surprised and forced to take part in the insurrection " . Of the 87 convicted , 39 were sentenced to death , five to deportation , 33 to life sentences of forced labour , nine to 20 years , and one to five years of forced labour . Among those condemned to death , 24 were civilians and 15 were servicemen . In France , the severity of the sentences led to a campaign by the French Communist Party and to various demonstrations by Vietnamese expatriates . At the time , more than 1 , 500 Vietnamese students were resident in France , particularly in Paris . In May , more than 1 , 000 demonstrated outside Elysee Palace against the French reaction to Yen Bay . The police arrested 47 and eventually deported 17 back to Vietnam , where most of them engaged in communist anti - colonial activities . Due to the high number of death sentences handed down , the Minister of Colonies intervened with Governor - General Pasquier , so that no execution could be performed unless the case had been reviewed by a pardoning commission . The presidential pardon reduced the quantity of death penalties pronounced at Yen Bay from 39 to 13 . Pardon was refused only to those who had killed a French officer , warrant officer , or a native soldier . The civilians benefited proportionately more from this intervention , as the enlisted soldiers had been responsible for most of the killings at Yen Bay . Among the 13 who were guillotined on June 17 , 1930 were the top VNQDD leaders , Hoc and Chinh . The condemned men cried " Viet Nam ! " as they were to be executed . Hoc made a last plea to the French in the form of a letter . In it , he claimed that he had always wanted to cooperate with the authorities , but that French intransigence had forced him to revolt . He contended that if France wanted to stay in Indochina , then it would have to drop policies that he termed as brutal , and become more amiable towards Vietnamese people . He called for the introduction of universal education , training in commerce and industry and an end to the corruption of the French - installed mandarins . The magazine ‘ ’ Phu Nu Tan Van ’ ’ ( ‘ ’ Women ’ s News ’ ’ ) disseminated pictures of the condemned VNQDD members in one of their issues , raising the stature of the revolutionaries in death . There were also penalties enacted against the French officers whose neglectful behaviour had contributed to the mutiny at Yen Bay . Resident Superior Robin released Resident Massimi from his duties immediately after the mutiny . No punishment was handed down to Commandant Le Tacon , the main person responsible for the security at Yen Bay which had failed to stop the mutiny . Neither Robin nor General Aubert , who were ultimately accountable for the failures of their subordinates , were punished . The former remained in Indochina as Governor General until retiring in 1936 . Aubert returned to France when his three year term ended in the autumn of 1930 . General Commandant Superior Aubert , who had been so lenient towards Le Tacon , organised an internal army purge in parallel with the trials of the Criminal Commissions . Its objectives were to reassert control over the native armed forces in Tonkin by identifying , penalising , isolating , and re - educating disloyal troops , thereby setting an example to the others . According to Patrice Morlat , " 545 tirailleurs and warrant officers were the object of sanctions : 164 were transferred into disciplinary companies in Tonkin , 94 to Africa . . . , 57 were handed over to the civilian jurisdiction , and 160 were reduced to the ranks and put on leave without pay . " Such remedial actions demonstrated the level of infiltration of the army , and clearly showed that the predominant culpability for the mutiny was seen to be placed squarely on the Vietnamese . In contrast with the first phase of suppression of the VNQDD in 1929 , when 121 soldiers suspected of having VNQDD membership were punished and 40 put under investigation by the Sûreté , the measures taken after Yen Bay were far more extensive and harsh . More than 500 out of Tonkin ' s 12 , 000 indigenous soldiers , a percentage of 4 . 5 % , were punished by the military , demonstrating the extent to which Vietnamese soldiers in the north were seen to be involved in activities contrary to their military duty . Impact on colonial rule . The impact of the mutiny on French rule was minimal , in the short and long term . The military casualties inflicted on the French army in the attack were in single figures and the attack did not generate widespread awareness among the populace , as the intended popular uprising did not occur . Instead , the attack backfired and saw a large number of VNQDD members killed , captured or executed . The subsequent French military and civilian crackdown saw military security increase and the VNQDD ' s ability to threaten French authority in Vietnam was extinguished . The vast majority of the leadership were killed or sentenced to death , and the remnants of the VNQDD fled to China , where several factions emerged under disparate leadership . In the long run , Yen Bay allowed the Indochinese Communist Party of Ho Chi Minh to inherit the VNQDD ' s status as the leading anti - colonial revolutionary movement . After the Second World War , an opportunity to fight for Vietnamese independence arose , and this allowed the communists in the Vietminh to dictate the platform of the independence movement . As a result , the communists were able to position themselves to become the dominant force in Vietnam post - independence . Military reforms precipitated by the mutiny . The mutiny refocused attention on the long term tension over the use of Indochinese soldiers , and on the ways in which it could be resolved . The tension could be traced back to the creation of French Indochina . Cochinchina , the European term for southern Vietnam , had been colonised in 1867 and the remaining parts of Vietnam , Tonkin and Annam , the northern and central regions were conquered in 1883 . Nominally , only Cochinchina was a colony , while Tonkin , Annam , Cambodia and Laos were protectorate s which together comprised French Indochina . The problem centred around the French reliance on native soldiers to maintain colonial control . This need was problematic because Indo - Chinese soldiers were both enforcers of colonial order and colonial subjects . This created constant French concerns about their loyalty . Despite several attempts to deal with the issue , the basic tension between the need for and suspicion of native troops could never be entirely resolved . The need for forces to pacify the countryside was too pressing to do without them . As a result , the tension resurfaced at regular intervals , either due to proposals to improve the position of Indochinese soldiers in the army , or after a mutiny had raised question marks about the loyalty of the soldiers . Background of Vietnamese troops in the French colonial army . The demand for Indochinese soldiers , auxiliaries first , and then regular troops , had been present since the beginning of French conquest . French troops were never numerically sufficient to assert control of the populace and then maintain " Pax Gallica " in the colony , thus requiring local reinforcements . French troops were too expensive compared to the substantially cheaper native troops . A lack of manpower back in Europe caused by other imperial programs and heavy casualties in World War I on the Western Front further caused a need for the recruitment of Indochinese troops . Because French Indochina was a domination and exploitation colony rather than a settler colony , there were insufficient local Frenchmen to build a settler - army . Native troops generally knew local conditions better , and could be used in terrain on which foreign troops were disadvantaged . Particularly after 1915 , French Indochina was expected to financially contribute to the defence of the colony and even to send native troops to France . The indigenous soldiers fulfilled a number of different purposes . Initially they were collaborators in the conquest of Indochina , helping to defeat the forces of the Nguyen Dynasty and then in its pacification . After the pacification campaign was officially completed in 1897 , the two main functions of the colonial army were the maintenance of internal peace and external security . Both these tasks were fulfilled in conjunction with other armed institutions , such as the " Garde indigène " ( later " indochinoise " ) , the gendarmerie , the police , and the irregular partisans in the border regions . The " Garde indigène " , a paramilitary force , was primarily responsible for dealing with disturbances of the peace and thus played an important role in the repression of public demonstrations and popular unrest . The participation of native soldiers in the colonial forces was used as political symbolism , proof that the Union ' s five territories were rightfully under French tutelage . This was the " blood toll " to be paid for the " Pax Gallica " . In their position as colonisers and colonial subjects , the native colonial troops were also buffers between the French and the unarmed populace . Their presence demonstrated French control and power to the ordinary population , deterring those who intended to violently overthrow French rule . The dilemma was that the French needed local soldiers to maintain their authority , but could not rely on them too deeply because of an innate fear that they would rebel or desert . These were deeply institutionalised in the army in the form of " safe " ratios of " white " and " yellow " soldiers , the segregation of the army , and barriers excluding Vietnamese from becoming officers until 1929 . The mutiny triggered the long existing fears about the loyalty of native soldiers , as well as many traditional French responses . Transfer of soldiers . In addition to the individual military punishments , the army took further internal measures to lower the risk of another insurrection . According to Maurice Rives , 10 , 000 Vietnamese troops were given transfers to different zones . This meant that more than 80 % of Tonkin ' s approximately 12 , 000 " Tirailleurs Tonkinois " were moved , a transfer of enormous proportions , indicating the extent of insecurity among French commanders towards Vietnamese troops , and the extent to which they were willing to go to make future Yen Bays impossible . One possible rationale for this measure was to break up any undiscovered VNQDD cells and to sever personal ties , within units and between soldiers and civilians in their local district . The mass transfer of soldiers also had the effect of creating a state of constant mobilisation , denying troops the time and opportunity for anti - colonial organisation . Aside from measures in Vietnam , 2 , 000 Indochinese soldiers returning from service in France were sent on indefinite leave and were not replaced with new recruits from Vietnam . The reason is put down by historians to be due to the fact that military discipline in France was less regimented than in Indochina and other colonial garrisons . In colonial units , the colonial military and social order with Frenchmen above their colonised troops was more easily reproduced . Metropolitan officers also treated their Vietnamese subordinates on a more equitable basis , making the Vietnamese less likely to accept the discrimination upon return to Vietnam . Overseas Vietnamese soldiers could become so alienated with their experiences that they became soft targets for communist propaganda . Upon returning home , they attempted to indoctrinate other troops with their Marxist doctrine . This train of thought further reinforced French perception that subversive ideas came from the outside rather than domestically : of the 57 soldiers involved in the mutiny , 17 had served abroad . On the other hand , according to the Thiry report , the proportion of soldiers with foreign service at Yen Bay did not exceed that in other garrisons , so this was not abnormal . Military intelligence reforms . In addition to punishing soldiers , tightening dismissal regulations and reducing the number of Vietnamese servicemen in France , the French decided to improve the military intelligence service . This was to be achieved by strengthening military intelligence through closer coordination with the Sûreté , and by raising internal standards . An inquiry into the mutiny at showed that cooperation between Resident Massimi and Commandant Le Tacon did not exist despite multiple requests , and that it was partly responsible for the uprising . The relationship between the civilian and military authorities were traditionally poor , but Yen Bay stood out in the total lack of military - civilian cooperation . Further VNQDD conspiracies to foment mutinies in other garrisons , such as Kien An , were detected and scotched at late notice . It was decided that the teamwork with the Sûreté had to be raised to greater heights to prevent future Yen Bay style rebellions . The rebellion allowed the civilian authorities an opportunity to involve themselves in military matters . The Sûreté ' s indirect penetration of military affairs involved linking the military intelligence service ( SRM ) to the Sûreté and the information provided by it , thereby making itself dependent on the political information and even political judgement and agenda of the civilian authorities . The central SRM then relayed this information to its local branches as part of its SRM Bulletin . As a result of the uprising , the SRM became more closely linked to the Sûreté and its methodology and philosophy in of analysing Vietnamese anti - colonial activity . It was further resolved to have all officers involved in studying revolutionary parties . The focus widened from observing only internal army activities to include developments among Vietnamese anti - colonial organisations at large . General Aubert cited complacency and laziness as a factor in the ineffectiveness of the officers in implement French intelligence strategy . He further asserted that the flow of intelligence between French officers and Vietnamese warrant officers was not as smooth as desired . He felt that his men were often not tactful and discreet enough ; citing a lack of language skills or interest in talking to their Vietnamese colleagues in an attempt to extricate information . Aubert also believed that the Vietnamese troops were effective in hiding their anti - colonial sentiments from their French colleagues . In addition to the measures intended to help identify , isolate or eliminate soldiers of suspect loyalty , the regulations for dismissal were liberalised . A decree of 8 April 1930 permitted the General Commandant Superior " to discharge those soldiers who had been the object of convictions in excess of three months imprisonment by a military tribunal , or who would have rendered themselves guilty of activities contrary to military duty " . Vietnamese language skills of French officers . Aubert ' s notice stressed the importance of close contact between French officers and their Vietnamese warrant officers in order to improve the quality of intelligence , but did not discuss whether this also required French officers to improve their Vietnamese language skills . The annual report of 1930 considered the language barrier was a problem . The report mentioned creating a Vietnamese studies centre in France to increase the proportion of Vietnamese - speaking French officers to enhance direct communication with their Vietnamese subordinates . However , the report principally had in mind the use of language skills as a tool of command to reinforce hierarchical relationships . The report also considered using specialised Vietnamese language skills as a means of gathering intelligence and to control the minds of Vietnamese troops , but discarded it , citing that infiltration and clandestine anti - colonial techniques were rendering them irrelevant . The report thus concluded that deeper specialisation would not improve intelligence , and that a degree of expertise – to improve command skills – was all that one would need . The report further argued that excessive specialization would be counterproductive and thus detrimental because it required long tours in Indochina , which was deemed to be detrimental to the health of the specialist . It also aired suspicions that specialists became too trusting towards their Vietnamese subordinates , to the extent of becoming indigenophiles . Finally , specialisation was said to be detrimental because it would not only make Vietnamese troops more secretive , but would very likely improve their organisational abilities , since they would need to " take even more precautions " . Decrease in the proportion of Vietnamese troops . Although the reaction , which included punishment , new regulations , SRM institutional reform , fewer Vietnamese serving in France , increased specialisation – were considerable , military and civilian authorities in both Vietnam and France did not believe them sufficient for the reassertion of control over their colonised troops . A further four decisions were implemented , aimed at striking the a stable racial balance among the troops in French Indochina . The number of ethnic Vietnamese soldiers was perceived to be too great and thus threatening in the wake of the mutiny . A safer proportion aimed at reducing the overall ratio among Indochina ' s colonial troops of 1 : 1 ethnic Vietnamese to European and indigenous ethnic minorities ( Montagnards ) was implemented . This demonstrated French distrust of Vietnamese troops and the apparent belief that the fidelity of Vietnamese soldiers was maximised by creating a racial balance within the army that was tilted towards showing all Vietnamese soldiers – and thereby the Vietnamese population at large – the futility of attempting insurrection and mutiny . The first of the four measures aimed at increasing the dependability of Vietnamese soldiers was also aimed at achieving the right ethnic proportion of troops at each garrison . The lack of European troops at Yen Bay had been pinpointed as the cause of the mutiny . The proposal held that the presence of more European troops at his disposal would have deterred the Vietnamese soldiers from taking part in the mutiny . The decision reversed a major reorganisation of the army that had been launched by General Aubert in 1928 . The measure was aimed to demonstrating French strength and superiority over Vietnamese soldiers and revolutionaries , that physical power was at the heart of French colonial rule in Indochina . The most sweeping suggestion was made by Resident Superior Robin who wanted to " completely and radically abolish all regiments of " Tirailleurs tonkinois " in the service in the delta and the middle regions " and relieve them with " white [ Foreign ] Legion or even North African Battalions " . This proposal was rebuffed by General Aubert , and eventually Governor General Pasquier eventually reached a compromise , which saw abolition of one Regiment of " Tirailleurs Tonkinois " . Policy strategists calculated that the reduction in Vietnamese troops could be made up by a concomitant increase in the number of European and ethnic minority troops . The third decision made with the objective achieving a safer racial ratio in the army was the " [ r ] einforcement of the occupation corps ' troops by three white battalions : one Foreign Legion battalion , [ and ] two Colonial Infantry battalions " . It was reasoned that if European troops were placed next to Vietnamese ones , then despite the reduction in Vietnamese troops by two battalions , more European troops would be needed . Since it was decided that the overall level of troops in Indochina could not be reduced for external defence reasons , this necessitated the replacement of at least the two disbanded Vietnamese battalions . Prior to the mutiny , the Department of War had clearly indicated that it would not be able " to provide for one more European Battalion in Indochina in the 1931 Budget " due to fiscal constraints , manpower shortages and organisational problems . The Yen Bay mutiny prompted generated the political will to send more European troops to French Indochina . The fear in the aftermath of the mutiny situation was such that a political decision was made to send two rather than one battalion . Aside from replacing two Vietnamese battalions with three French battalions , the French authorities also increased the number and proportion of ethnic minorities among the Indochinese troops . As such , the " [ i ] ntensification of recruitment of non - Annamite indigenous people : Thos , Laotians , Mois , Cambodians was decided . " The aim was to increase the non - Vietnamese percentage to 50 % .