The Zara-class heavy cruisers were designed to have improved protection over the Trento-class, at the cost of speed. Originally designated light, then armoured, the Zara-class was properly rated as heavy cruisers. They were intended to remain within the 10,000-ton limits of the Washington treaty but eventually crept up by more than 10% of that limit. Pola, Zara and Fiume were lost in action with British forces off Cape Matapan while Gorizia passed into German hands upon the Italian surrender and was eventually sunk by British and Italian frogmen using Chariot mini-subs.