Formosa expeditionary corps remained confined in Keelung, the French scored important successes elsewhere in the spring of 1885. Courbet's squadron had been reinforced substantially since the start of the war, and he now had considerably more ships at his disposal than in October 1884. In early February 1885 part of his squadron left Keelung to head off a threatened attempt by part of the Chinese Nanyang Fleet (Southern Seas fleet) to break the French blockade of Formosa. On 11 February Courbet's task force met the cruisers Kaiji, Nanchen and Nanrui, three of the most modern ships in the Chinese fleet, near Shipu Bay, accompanied by the frigate Yuyuan and the composite sloop Chengqing. The Chinese scattered at the French approach, and while the three cruisers successfully made their escape, the French succeeded in trapping Yuyuan and Chengqing in Shipu Bay. On the night of 14 February, in the Battle of Shipu, the French attacked the Chinese vessels with two torpedo launches. During a brief engagement inside the bay, Yuyuan was seriously damaged by torpedoes and Chengqing was hit by Yuyuan'''s fire. Both ships were subsequently scuttled by the Chinese. The French torpedo launches escaped almost without loss. Courbet followed up this success on 1 March by locating Kaiji, Nanchen and Nanrui, which had taken refuge with four other Chinese warships in Zhenhai Bay, near the port of Ningbo. Courbet considered forcing the Chinese defences, but after testing its defenses finally decided to guard the entrance to the bay to keep the enemy vessels bottled up there for the duration of hostilities. A brief and inconclusive skirmish between the French cruiser Nielly and the Chinese shore batteries on 1 March enabled the Chinese general Ouyang Lijian (歐陽利見), charged with the defence of Ningbo, to claim the so-called 'Battle of Zhenhai' as a defensive victory. In February 1885, under diplomatic pressure from China, Britain invoked the provisions of the 1870 Foreign Enlistment Act and closed Hong Kong and other ports in the Far East to French warships. The French government retaliated by ordering Admiral Courbet to implement a 'rice blockade' of the Yangzi River, hoping to bring the Qing court to terms by provoking serious rice shortages in northern China. The rice blockade severely disrupted the transport of rice by sea from Shanghai and forced the Chinese to carry it overland, but the war ended before the blockade seriously affected China's economy.