The Marcilio Dias class destroyers (sometimes referred to as M class) were three ships of the Brazilian Navy that served during World War II. They were based on the Mahan class destroyer and were the first sizable ships built in Brazil. One 5 inch gun and one bank of torpedo tubes were removed to improve stability soon after completion and extra AA guns and radar were fitted. In the 1960s a Sea Cat missile system was fitted to Mariz e Barros.