After Italy entered World War II in June 1940, "Trento" and "Trieste" saw extensive action against British forces in the Mediterranean Sea, including at the battles of Calabria, Cape Spartivento, and Cape Matapan in July and November 1940 and March 1941, respectively. "Trento" was present at Calabria, where she battled British cruisers but did not sustain any damage. At the Battle of Cape Spartivento, either "Trento" or "Trieste" scored a hit on the British cruiser , and "Trieste" was briefly engaged but not seriously damaged by the battlecruiser . At Cape Matapan, the two cruisers engaged several British cruisers at very long range, with neither side scoring any hits.