During World War II the Italian city of Naples suffered approximately 200 air raids by the Allies from 1940 to 1944; only Milan was attacked more frequently. Almost all of the attacks — a total of 181 — were launched in the first nine months of 1943 before the Four days of Naples and the Allied occupation of the city at the beginning of October. Estimates of civilian casualties vary between 20,000 and 25,000 killed. Naples was a major strategic objective in the Mediterranean and Middle East theatre of World War II and the Italian campaign. Its port was a principal trading connection to Africa, as well as a center of industry and communication. Naples also harbored an Italian military fleet, like the cities of Taranto and La Spezia. As the first large Italian city in the way of the Allies' Operation Avalanche, Naples increased in importance in 1943. In Naples, the primary targets were the port facilities at the extreme eastern end of the Port of Naples as well as the rail, industrial and petroleum facilities in the eastern part of the city and the steel mill to the west, in Bagnoli. The French bombing began with four bombardments between 10 and 15 June 1940. The first English bombardment (after aerial reconnaissance) began on 1 November 1940, between the hours of 4:20 and 6:20 in the morning. It was conducted by the Bristol Blenheim] light bombers of the Royal Air Force from their base in Malta. Several days later came the Battle of Taranto, also in southern Italy. These first bombardments struck, above all, the Zona Industriale (for the fuel and refineries there) and areas near the Napoli Centrale railway station. The following bombardments concentrated on the port and ships, also near the Zona Industriale, which included the neighborhoods of San Giovanni a Teduccio, Bagnoli, Pozzuoli. Naples, as a whole, was not yet fortified against attack: the city had few air raid shelters and the only anti-air weapons it had were the ship cannons in the port. The next bombing came on 8 January 1941, and lasted around three hours.