The Battle of Tamsui (2–8 October 1884) was a significant French defeat by the Qing dynasty at Tamsui on Taiwan during the Keelung Campaign of the Sino-French War. The failure of the attack was an embarrassing setback to the French. Captain Garnot later blamed the defeat on the small size of the landing force, and on the use of naval landing companies rather than trained infantry.

The French defeat at Tamsui was of considerable political significance. China's war party had been placed on the defensive after the loss of China's Fujian fleet in the Battle of Fuzhou on 23 August 1884, but the unexpected Chinese victory at Tamsui six weeks later bolstered the position of the hardliners in the Qing court. A court conference convened by the Empress Dowager Cixi on 28 October decided to continue the war against France until the French withdrew their demand for the payment of an indemnity for the Bac Le ambush. On 5 November the Qing court offered the French peace terms so extreme that they had no chance whatever of being accepted.