The Italians and Austro-Hungarians fought there in one of the nastiest fronts of the war, the 12 Battles of the Isonzo, with a total of 1.2 million casualties.
Italy had used up so many men in WWI that it still hadn’t recovered by WWII. With a population of about 35 million, they had lost about 1.25 million people, with another million military wounded.
These were military deaths, all concentrated within a single generation, males in their twenties.