France and China had begun to fight…
March 1884 CE
France and China had begun to fight an undeclared war in Tonkin in late 1883.
The French had defeated the Black Flag Army and captured the town of Son Tay in December 1883, in the Son Tay Campaign.
In the Bac Ninh campaign of March 1884, they defeat China's Guangxi Army and capture the strategically important town of Bac Ninh on the Mandarin Road.