Zara, Georg von Trapp’s birthplace became Italian after WWI and was absorbed by Yugoslavia after WWII.
Von Trapp was a submariner. During WWI his U-boat sank a French cruiser and an Italian submarine.
By the Treaty of London in 1915, Italy was promised large chunks of Austrian territory if it entered the war on the side of the Allies. Italy did enter the war, although it isn't clear that that aided the Allies. Afterwards at the Paris Peace Conference Italy wanted its reward, and got Trieste, Istria, Zadar ("Zara"), and some of the Adriatic islands. Woodrow Wilson opposed most of those demands because the Italians were generally only a small fraction of the population in those areas. They were a majority in the city of Trieste and in the city of Zadar but the surrounding countryside was non-Italian.
In 1941 Hitler gave additional areas to Italy after the German conquest of Yugoslavia, which Italy gave up after it switched sides in 1943. Tito tried to grab Trieste in 1945 but was forced to remove his troops after 40 days. Zadar, Istria, Rijeka, and the Adriatic islands went to Yugoslavia.
Istria still has an Italian-speaking minority but I don't know about Zadar.