armored belt that was thick at the waterline and reduced to at the bottom edge of the belt. Their main armor deck was thick, and the box formed by the belt and deck was capped at either end by armored bulkheads that were thick in the upper portion and in the lower section. The main deck was supplemented with an upper deck that was thick, which was intended to detonate the fuses of incoming shells before they struck the main deck; the upper deck was connected to an upper belt that was thick. The gun turrets had 150 mm thick plating on the faces and the barbettes they sat in were also 150 mm thick. The main conning tower had 150 mm thick sides and an thick roof. The Zara class carried three times the armor protection of the preceding Trentos. Their heavy armor made the Zaras the best-protected cruisers until the introduction of the , laid down in 1945 by the United States. This additional armor would have made the ships decidedly nose-heavy, so to offset this the rear of the ship was raised by one deck behind the front funnel. The result was excellent watertight integrity and protection. Ships Service history After entering service in the early 1930s, the four members of the Zara class took part in training exercises with the Italian fleet and participated in fleet reviews held for foreign leaders, including Adolf Hitler of Nazi Germany and Miklós Horthy, the Regent of Hungary. Gorizia and Pola were involved in the Spanish Civil War; in 1936 Pola conducted non-intervention patrols and Gorizia carried Italian nationals from Gijon, Spain, to Le Verdon-sur-Mer, France that year. After departing France, Gorizia visited Germany, and on the way back, she suffered a major explosion in an aviation gasoline tank that forced her to put into Gibraltar for repairs. There, British shipyard inspectors discovered that the ship was grossly over the Washington Treaty's displacement restriction. In March 1939, all four ships sortied to prevent a squadron of Republican warships from reaching the Black Sea, forcing them to stop in Bizerte, Tunisia, where they were interned. The following month, Zara, Pola, and Gorizia provided gunfire support to Italian forces invading Albania. The Zara-class cruisers saw extensive service during World War II, having taken part in several sorties to catch British convoys in the Mediterranean as the flagship of the 1st Division. At