Battle of Gia Cuc The Battle of Gia Cuc , fought on 27 and 28 March 1883 , was a battle in the Tonkin Campaign between the French and Vietnamese , during the period of undeclared hostilities that preceded the Sino - French War ( August 1884 – April 1885 ) . Background . 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 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 Lang Son , Bac 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 . Both negotiators were criticized for giving too much away , and the deal soon unravelled . It was never ratified in China , and in France Jules Ferry ' s incoming administration disavowed the agreement in March 1883 and recalled Bourée . 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 Dinh with a flotilla of gunboats and a force of 520 French soldiers under his personal command . The Battle of Gia Cuc was precipitated by an attempt by the Vietnamese commander Prince Hoang Ke Viem , with limited assistance from Liu Yongfu ' s Black Flag Army , to capture Hanoi from the French during Rivière ' s absence at Nam Dinh with the bulk of the available French forces . The battle . On 27 and 28 March the commander of the Hanoi garrison , " chef de bataillon " Berthe de Villers , sallied out against Prince Hoang ' s Vietnamese army , around 6 , 000 strong , with two companies of marine infantry and a small force of sailors from the gunboat " Léopard " , leaving behind a single company of marine infantry to garrison the Royal Palace . Using intelligent fire and movement tactics and supported by " Léopard " ' s artillery , the French attacked the Vietnamese defences , captured the villages of Gia Thuy and Gia Cuc , and finally drove the Vietnamese from the battlefield . French casualties were 4 men wounded . The Vietnamese may have lost as many as 1 , 000 dead and wounded . One of the factors in the Vietnamese defeat was the absence of serious pressure on the French from Liu Yongfu ( Liu Yung - fu , 劉永福 ) and the Black Flag Army . Liu was supposed to attack Hanoi from the west while Prince Hoang descended from the north . However , the two men were on the coolest of terms , and Liu made only a feint attack on the French - held Royal Palace . This attack was easily beaten off by the French garrison . Significance . Berthe de Villers ' remarkable victory at Gia Cuc , coupled with Rivière ' s simultaneous Capture of Nam Dinh , demoralised the Vietnamese , appreciably raised French prestige in Tonkin , and emboldened French policymakers to shrug off the growing prospects of direct Chinese intervention in Tonkin . Meanwhile , the failure of cooperation between Prince Hoang and Liu Yongfu alarmed the Chinese . The senior Chinese civil mandarin Tang Jingsong ( Tang Ching - sung ) reconciled the two men in April 1883 , and persuaded Liu Yongfu to take the field against the French with the Black Flag Army . The result , in May 1883 , was the disastrous French defeat at the Battle of Paper Bridge , in which both Rivière and Berthe de Villers were killed .