During World War II the regiment was assigned to the 57th Infantry Division "Lombardia", with which it participated in the Invasion of Yugoslavia.

Afterwards the division remained in occupied Yugoslavia until it was disbanded by invading German forces after the announcement of the Armistice of Cassibile on 8 September 1943.

[3][4] After the annexation of Lombardy the Royal Sardinian Army began to form new regiments with personnel levied in the region.

[2][3][4] In the 1860-1861 the brigade participated in the campaign in central and southern Italy, where the regiment fought at Spoleto and in the Battle of Mola.

For its conduct during the storming of the fortress of Albornoziana in Spoleto the 3rd Grenadier Regiment was awarded a Silver Medal of Military Valor.

In 1895-96 the regiment provided four officers and 203 enlisted for units deployed to Italian Eritrea for the First Italo-Ethiopian War.

At the time the 73rd Infantry Regiment consisted of three battalions, each of which fielded four fusilier companies and one machine gun section.

After Italy's entry into the war on 23 May 1915 the Brigade "Lombardia" was deployed to the Italian front: in June 1915 the regiment fought in the First Battle of the Isonzo against Austro-Hungarian forces on Monte Peuma.

In November 1916 the brigade fought in the Ninth Battle of the Isonzo, during which it managed to take and hold the summits of the Pečinka and Veliki Hribach.

For taking the three summits the two regiments of the Brigade "Lombardia" were both awarded a Gold Medal of Military Valor.

In August of the same year the brigade fought in the Eleventh Battle of the Isonzo on the slopes of Fajtji hrib.

In October-November 1918 the brigade fought in the decisive Battle of Vittorio Veneto on the ridge of Monte Solarolo.

After the announcement of the Armistice of Cassibile on 8 September 1943 the division skirmished with Germans forces, while trying to reach Rijeka and Ilirska Bistrica in Italy.

In case of war the regiment was tasked with manning fortifications of the Alpine Wall on the Tagliamento river between Trasaghis and Latisana.

[2] On 1 November 1973 the regiment was reduced to LXXIII Infantry Fortification Battalion "Lombardia" based in Arzene.

On 1 October 1986 the Armored Division "Ariete" was disbanded and two battalions were assigned to the 8th Mechanized Brigade "Garibaldi".