Mers-el-Kebir (mĕrs-ĕl-kəbĭr`), town, NW Algeria, on the Gulf of Oran. Originally a Roman port, it has a long history of maritime importance. During the 15th cent. it was a center of activity for corsairs and was twice occupied by the Portuguese. The Spanish held the town from 1505 to 1792; the French arrived in the 19th cent. After France's defeat by Germany in June, 1940, the French fleet sought refuge at Mers-el-Kebir, but the British navy sank or damaged most of the ships. The great French naval base at Mers-el-Kebir came to include subterranean installations where atomic tests were held. In 1962 the Evian Agreement, by which Algerian independence was acknowledged, allowed France to maintain the Mers-el-Kebir base for 15 years; however, the French evacuated the base in 1967.