At the start of the participation of Italy in World War I (May 1915), the 3rd Army occupied the southern part of the Isonzo Front.
It was commanded by Prince Emanuele Filiberto, Duke of Aosta and consisted of the The 3rd Army participated in all eleven Battles of the Isonzo (1914-1917).
It withdrew in relative good order during the Caporetto disaster of October 1917 and played a leading role in the final victory offensive a year later.
[2] In June 1940, the 3rd Army was formed and based in Southern Italy, Sicily and Sardinia.
[citation needed] However with the easing of tensions between Italy and Yugoslavia, which culminated in the division of the Trieste Free Territory with the Treaty of Osimo, the army decided to disband the command designated "3rd Army", along with VI Army Corps on 31 March 1972, with all the functions of higher command resting with LANDSOUTH from that date onward.