The name of Ninh Binh officially existed since 1822. During the Nguyen dynasty, in August 1884 in the Tonkin campaign, the allegiance of Ninh Bình was of considerable importance to the French, as artillery mounted in its lofty citadel controlled river traffic to the. Gulf of Tonkin. Although the Vietnamese authorities in Ninh Bình made no attempt to hinder the passage of an expedition launched by Henri Riviere in March 1883 to capture Nam Dinh. they were known to be hostile towards the French. In November 1883, on the eve of the Son Tay campaign. the French occupied the citadel of Ninh Bình without resistance and installed a garrison.