Battle of Ky Hoa The Battle of Kỳ Hòa ( Trận Đại đồn Chí Hòa ) on 24 and 25 February 1861 was an important French victory in the Cochinchina campaign ( 1858 – 62 ) . This campaign , fought between the French and the Spanish on the one side and the Vietnamese on the other , began as a limited punitive expedition and ended as a French war of conquest . The war concluded with the establishment of the French colony of Cochinchina , a development that inaugurated nearly a century of French colonial dominance in Vietnam . Background . After early French victories at Tourane and Saigon , the Cochinchina campaign reached a point of equilibrium with the French and their Spanish allies besieged in Saigon , which had been captured by a Franco - Spanish expedition under the command of Admiral Charles Rigault de Genouilly on 17 February 1859 . The arrival of massive reinforcements from the French expeditionary corps in China in 1860 allowed the French to break the Siege of Saigon and regain the initiative . The end of the Second Opium War in 1860 allowed the French government to despatch reinforcements of 70 ships under Admiral Léonard Charner and 3 , 500 soldiers under General de Vassoigne to Saigon . Charner ' s squadron , the most powerful French naval force seen in Vietnamese waters before the creation of the French Far East Squadron on the eve of the Sino - French War ( August 1884 – April 1885 ) , included the steam frigates " Impératrice Eugénie " and " Renommée " ( Charner and Page ' s respective flagships ) , the corvettes " Primauguet " , " Laplace " and " Du Chayla " , eleven screw - driven despatch vessels , five first - class gunboats , seventeen transports and a hospital ship . The squadron was accompanied by half a dozen armed lorchas purchased in Macao . The battle of Ky Hoa . The French and their Spanish allies were besieged in Saigon by a Vietnamese army around 32 , 000 strong under the command of Nguyen Tri Phuong . The Vietnamese siege lines , 12 kilometres long , were centred on the village of Ky Hoa ( Vietnamese : Kỳ Hòa ) , and were known to the French as the ' Ky Hoa lines ' . Ky Hoa itself had been transformed into a formidable entrenched camp : The first objective was the capture of the entrenched camp of Ky Hoa . This was a rectangle measuring around 3 , 000 metres by 900 metres , divided into five compartments separated by traverses and enclosed within walls three and a half metres high and two metres thick . The camp was armed with more than 150 cannon of all calibres . Subsidiary defences were piled up in front of its walls : wolf - pits , ditches filled with water , palisades and chevaux de frise . Bamboo was employed in the defences with consummate art , and the walls were crowned with thorn bushes along their entire length . The number of enemy soldiers both in and around the fortified camp had grown steadily during the previous year . After the victory , we discovered from the muster rolls that there were 22 , 000 regular troops and 10 , 000 militiamen . There were also 15 , 000 men manning the forts along the upper course of the Donnai . All these men were under the command of Nguyen Tri Phuong , the most celebrated general in the Annamese army . On 24 and 25 February 1861 the French attacked and captured the Ky Hoa lines . The first assault was made on 24 February . The French artillery moved forward to a position one kilometre from the siege lines , and bombarded the Vietnamese defences . The French and Spanish infantry formed up behind the artillery positions in battalion columns . Then , at the canter , the mountain guns advanced to within 500 metres of Redoubt Fort ( " fort de la Redoute " ) and the line of entrenchments that stretched away to the east . The rest of the artillery soon followed them , and when the infantry reached this new line it split up into two assault columns , the soldiers to the right led by " chef de bataillon du génie " Allizé de Matignicourt , and the sailors on the left under the command of " capitaine de frégate " Desvaux , captain of the transport " Entreprenante " . The French and Spanish assault columns charged , and captured Redoubt Fort and part of the Vietnamese trench lines . However , the attackers suffered heavily from Vietnamese fire . The French commander General de Vassoigne and the Spanish commander Colonel Palanca y Guttierez were both wounded in the attack . A second assault was made on 25 February . The attack was made at dawn , by two columns of infantry supported by artillery . Thomazi gave the following description of the assault . The action resumed at 5 a . m . on 25 February . The artillery advanced , facing east , enclosed by two columns of infantry : to the left , the engineers , the marine infantry and the " chasseurs " ; to the right the Spanish infantry and the sailors . The sun , very low in the sky , was spoiling the aim of the cannons , and Lieutenant - Colonel Crouzat brought them forward by rapid bounds to within 200 metres of the enemy lines and ordered them to fire with case shot at the top of the ramparts . The firing was very heavy and our men , in the open , suffered appreciable casualties . Then the haversacks were laid on the ground , the sailors of the assault force reclaimed their scaling ladders , up to then carried by the coolies , and the admiral ordered the charge to be sounded . The right column , led by " capitaine de vaisseau " de Lapelin , crossed the wolf pits , the ditches and the chevaux de frise which extended for more than 100 metres in front of the enemy work under an intense fire , and was the first to reach the parapet . Most of the scaling ladders , which were very light , had been broken during the advance . Only three were left , which were placed along the wall , and the sailors of the assault force who could not find a place there climbed on the shoulders of their comrades . This time the fighting was bitter indeed . The first men to reach the summit were killed , but others took their place , throwing grenades inside . Then , using grappling hooks , they breached the perimeter fence and entered the fort . They then found themselves in an enclosed compartment swept by the fire from the neighbouring compartment , to which they could make no reply . It was a critical situation , and they suffered heavy losses . Finally , several resolute men , rallied by " lieutenant de vaisseau " Jaurès , succeeded in smashing in the gate that gave onto the other compartment with their axes , just as the engineers succeeded in breaking in , while the marine infantry and the chasseurs outflanked the enemy line on the left . The defenders were either killed where they stood or took to flight . The entire complex of the Ky Hoa lines had fallen into our hands . Once again , French and Spanish casualties were relatively heavy ( 12 dead and 225 wounded ) . Many of the wounded , including Lieutenant - Colonel Testard , a marine infantry officer , later died as a result of their wounds . According to the French , the Vietnamese lost around 1 , 000 men , and their casualties included Nguyen Tri Phuong , who was wounded during the battle . Aftermath . The victory at Kỳ Hòa allowed the French and Spanish to move to the offensive . In April 1861 , Mỹ Tho fell to the French . In early 1862 the French captured Biên Hòa and Vĩnh Long . These victories forced the Vietnamese to sue for peace in April 1862 . By then the French were not in a merciful mood . What had begun as a minor punitive expedition had turned into a long , bitter and costly war . It was unthinkable that France should emerge from this struggle empty - handed , and Tự Đức was forced to cede the three southernmost provinces of Vietnam ( Biên Hòa , Gia Định and Định Tường ) to France . Thus , casually , was born the French colony of Cochinchina , with its capital at Saigon .