[2] Two months before the start of the Great War, he was tasked with forming the XIV Army Corps, at the head of which, at the beginning of hostilities, he was positioned on the Isonzo front at Monte San Michele.

He managed to hold the position thanks to his skills as a tactical organizer and leader of rank and file soldiers, mostly from the south of Italy.

[2][4] Morrone liaised with Cadorna and articulated in cabinet his authoritarian approach to the war, sharing his suspicion about the 'home front' and issuing circulars that reflected the preoccupations of the supreme command towards 'defeatism’.

[5] They were replaced by General Gaetano Giardino, close to Cadorna, at the Ministry of War and by Vice Admiral Arturo Triangi at that of the Navy.

Subsequently he commanded the IX Army, held as a general reserve, [6] without participating in the final battle of Vittorio Veneto.

[7][8] At the end of 1920 he was one of a group of generals invited by Minister of War Ivanoe Bonomi to assist with reform of the high command.

Morrone was among those who approved the new structure based on the French model of collegiate leadership that took effect in February 1921 with the resignation of Pietro Badoglio as chief of staff.