The Battle of Yu Oc (19 November 1884) was a French victory during the Sino-French War. The battle was fought to relieve the French garrison of Tuyen Quang, under siege by the T'ang Ching-sung's Yunnan Army and Liu Yongfu's Black Flag Army. The French commander at Yu Oc, Colonel Jacques Duchesne, would later distinguish himself as the conqueror of Madagascar (1895).