On 23 May 1915, between two and four hours after the Italian declaration of war reached the main Austro-Hungarian naval base at Pola, "Radetzky" and the rest of the fleet departed to bombard the Italian and Montenegrin coast. Their focus was on the important naval base at Ancona, and later the coast of Montenegro. The bombardment of Montenegro was part of the larger Austro-Hungarian campaign against the Kingdoms of Montenegro and Serbia, who were members of the Entente, during the first half of 1915. During the attack on Ancona and the surrounding coastline, "Radetzky", as well as the cruisers and , and the destroyers , , and traveled south to cover the ships attacking Ancona. Upon finding no enemy ships in the region, the group bombarded the Termiti Islands, Viests, Manfredonia, and Barletta. After leaving the Gulf of Manfredonia "Radetzky" and the rest of the ships accompanying her sighted the first enemy ships of the day, two Italian destroyers. During the encounter, one Italian destroyer managed to escape the Austrian ships but the other, , was severely damaged. Only when a larger Italian force appeared did "Radetzky" and her accompanying ships abandon their attempts to capture the damaged destroyer.