On 15th September 1936 the 4th Tank Driver Infantry Regiment was constituted, including the assault tanks battalion then called light (L) and medium (M).
Sent to Northern Africa, it was dissolved on 25th January 1941 after having deserved the maximum recognition to the Military Valour. Reconstituted on 15th March 1941 in Rome by transformation of the Deposit Troops Command, it provided for the constitution of numerous units and later dissolved on 8th September 1943.
On 1st January 1953 the 4th Tank Drivers Regiment of the "Pozzuolo del Friuli" Armoured Division becoming 4th Armoured Infantry Regiment on 1st May 1958 and included in the "Legnano" Division, until its dissolution on 29th October 1975.
The 20th Tanks Battalion still remained as 20th "M.O. Pentimalli" Tanks Battalion of the "Legnano" Mechanized Brigade that took the regiment Flag and traditions.
Dissolved on 30th January 1991, it was reconstituted on 18th September 1992 in Ozzano Emilia for the "Friuli" Brigade. Dissolved again on 1st September 1993, it was reconstituted with the 6th Tanks Battalion of the "Grenadiers of Sardinia" Brigade in Civitavecchia, substituted in 1996 by the reconstituted 20th Battalion.
In Civitavecchia it was dissolved another time before being reconstituted for the "Centauro" Mechanized Brigade in Bellinzago Novarese.
It was then incorporated in the "Ariete" Brigade.