After the war the regiment was based in the newly annexed province of South Tyrol.

[2] The 231st Infantry Regiment (Brigade "Avellino") was formed during World War I on 6 May 1916 in Camposampiero near the Italian Front.

The regiment consisted of three battalions, which each fielded four fusilier companies and one machine gun section.

In May 1917 the brigade fought in the Tenth Battle of the Isonzo, during which it conquered Zagomila and Zagora, and participated in the conquest of Mount Vodice.

In October 1918 the brigade fought in the Battle of Vittorio Veneto, initially at Romanziol, and after the Italian breakthrough of the Austrian lines at Motta di Livenza and then at the bridge over the Tagliamento river at Madrisio.

As the regiments of the Avellino had no regimental depots of their own, the brigade moved in 1920 to the newly conquered region of South Tyrol, with the 231st taking over the barracks of the Austro-Hungarian Army in Meran and the 232nd taking over the barracks in Bolzano.

In 1935 the 18th Infantry Regiment "Acqui" moved from Trento to Brixen in South Tyrol.

[2][6][7] At the outbreak of World War II the regiment consisted of a command, a command company, three fusilier battalions, a support weapons battery equipped with 65/17 infantry support guns, and a mortar company equipped with 81mm Mod.

For its conduct during this war the 231st Infantry Regiment "Brennero" was awarded a Bronze Medal of Military Valor, while the 232nd Infantry Regiment "Brennero" was awarded a Silver Medal of Military Valor.

[2][6][7] After the war the Brennero division was tasked with counter-insurgency and police duties in Athens, while 231st Infantry Regiment "Brennero" remained in Albania, where it was assigned to the 41st Infantry Division "Firenze" for anti-partisan duties.