On 6 June, the Azio-class minelayer "Ostia" used 470 mines to lay eight barrages off Massawa and the destroyer "Pantera" dropped 110 mines in two barrages off Assab the day after. When Italy declared war on 10 June, "Galileo Ferraris" sailed for French Somaliland (Djibouti), "Galileo Galilei" to Aden, "Galvani" to the Gulf of Oman and "Mecallé" to Port Sudan. On 14 June "Evangelista Torricelli" put to sea to relieve "Galileo Ferraris" whose crew had been incapacitated by chloromethane poisoning from the refrigeration system. The crew of "Macallé" was also afflicted; the boat was run aground and lost on 15 June. On 18 June, "Galileo Galilei" boarded and released the neutral Yugoslav steamship "Dravo" and the next day engaged the armed trawler off Aden. All but one officer was killed by shell-fire and the boat was captured along with many documents including the orders for four more Italian submarines.