Every year in Slovenia, September 15 is celebrated as the Day of the reunification of Primorye with the Fatherland.
Slovenian Littoral (Slovene Primorska) is the western part of Slovenia, which historically was part of the country. It is adjacent to the Adriatic Sea and consists of two historical regions - Istria and Gorica. Before the formation of Yugoslavia, these lands were part of the Habsburg crown region of the Austrian Littoral.
By the beginning of the First World War, the population of the Slovenian Primorye was more than 300 thousand inhabitants. As a result of the war, these lands were occupied by Italy and included in its composition, despite fierce battles and defeats on neighboring fronts.