As the British advanced toward Eritrea during their East African Campaign in World War II, Mario Bonetti—the Italian commander of the Red Sea Flotilla based at Massawa—realized that the enemy would overrun his harbor. In the first week of April 1941, he began to destroy the harbor's facilities and ruin its usefulness to the British. Bonetti ordered the sinking of two large floating dry docks and supervised the calculated scuttling of eighteen large commercial ships in the mouths of the north Naval Harbor, the central Commercial Harbor and the main South Harbor. This blocked navigation in and out. He also had a large floating crane scuttled. These actions rendered the harbor useless by 8 April 1941, when Bonetti surrendered it to the British. Scuttled ships included the German steamers "Liebenfels", "Frauenfels", , "Crefeld", "Gera" and "Oliva". Also scuttled were the Italian steamers "Adua", "Brenta", "Arabia", "Romolo Gessi", "Vesuvio", "XXIII Marzo", "Antonia C.", "Riva Ligure", "Clelia Campenella", "Prometeo" and the Italian tanker "Giove". The largest scuttled vessel was the 11,760-ton "Colombo", an Italian steamer.