In the interwar period, the two cruisers served in the Cruiser Division, frequently alternating as the divisional flagship. "Trento" made two extensive trips abroad, the first was a tour of South American countries in mid to late-1929 and the second was a deployment to China to protect Italian nationals during the Chinese Civil War. In 1938, "Trieste" assisted in the repatriation of Italian volunteer soldiers who had fought in Spain during the Spanish Civil War. Both ships saw extensive action in World War II, including the battles of Calabria, Cape Spartivento, and Cape Matapan. "Trieste" was damaged by a British submarine in November 1941 and therefore missed the First and Second Battles of Sirte, where at the latter action "Trento" damaged a British destroyer.