Formation On 1 August 1862 the
45th Infantry Regiment (
Brigade "Reggio"),
46th Infantry Regiment (Brigade "Reggio"),
47th Infantry Regiment (
Brigade "Ferrara"),
48th Infantry Regiment (Brigade "Ferrara"), 49th Infantry Regiment (
Brigade "Parma"), and 50th Infantry Regiment (Brigade "Parma") ceded their 17th Company and 18th Company to help form the 66th Infantry Regiment (
Brigade "Valtellina") in
San Maurizio Canavese. The twelve companies were grouped into three battalions. On the same date the
53rd Infantry Regiment (
Brigade "Umbria") and the 54th Infantry Regiment (Brigade "Umbria") ceded both a depot company to help form the new regiment's
depot in
Turin, while the 3rd Provisional Depot in
Bagheria in
Sicily provided four companies to form the regiment's IV Battalion, which initially remained based in Bagheria. The regiment was assigned, together with the 65th Infantry Regiment, to the Brigade "Valtellina" in Turin. The brigade's command and the 65th Infantry Regiment had also been formed on 1 August 1962, with the 25th Infantry Regiment (
Brigade "Bergamo"),
26th Infantry Regiment (Brigade "Bergamo"),
41st Infantry Regiment (
Brigade "Modena"), 42nd Infantry Regiment (Brigade "Modena"), 55th Infantry Regiment (
Brigade "Marche"), and 56th Infantry Regiment (Brigade "Marche") ceding their 17th Company and 18th Company to help form the three battalions of the 65th Infantry Regiment, while the
52nd Infantry Regiment (
Brigade "Alpi") and the 61st Infantry Regiment (
Brigade "Sicilia") provided both a depot company. The 65th Infantry Regiment's IV Battalion was also formed in
Sicily with four companies provided by the 2nd Provisional Depot in
Palermo. Initially the regiment's IV Battalion remained based in Palermo. In 28 February 1918 the depot of the regiment in Reggio Emilia formed the brigade command of the
Brigade "Treviso" and the command of the 100th Infantry Regiment (Brigade "Treviso"). In fall 1918 the brigade operated in the
Val d'Assa valley, where in October the brigade fought on
Cima Tre Pezzi. In 1934 the 8th Territorial Division of Piacenza changed its name to
8th Infantry Division "Po", while the 16th Territorial Division of Bologna changed its name to
16th Infantry Division "Fossalta". The name change that also extended to the two divisions' infantry brigades. In 1935–36 the regiment provided four officers and 1,079 enlisted for units deployed for the
Second Italo-Ethiopian War. The division lost two regimental commanders before being partly overcome by British attacks, but the delay of the Allied advance allowed German armored forces to launch a devastating counterattack. During the
Battle of Alam el Halfa the Trieste was in the center of the Axis advance, but stiff British resistance forced General Erwin Rommel to abandon the battle. On 23 October 1942 the British commenced the
Second Battle of El Alamein and the Trieste initially formed the reserve in the North of the Axis line. On 26 October the Trieste entered the front line. On 2 November British forces broke through the Trieste's line and a 4–5-km gap opened between the battalions of the 65th Infantry Regiment "Trieste". Most of the Trieste was annihilated over the course of the next two days. On 4 November the division's command and most of the 66th Infantry Regiment "Trieste" retreated to
Fuka and thus escaped the destruction of Axis forces at El Alamein.
Cold War During the
1975 army reform the army disbanded the regimental level and newly independent battalions were granted for the first time their own flags. On 30 September 1975 the
40th Infantry Regiment "Bologna" in
Bologna was disbanded and the next day the regiment's II Battalion in
Forlì Veronese was reorganized and renamed
66th Mechanized Infantry Battalion "Valtellina" and assigned the flag and traditions of the 66th Infantry Regiment "Trieste". To avoid confusion with support units of the
Mechanized Brigade "Trieste" the battalion's name was changed from "Trieste" to its original name "Valtellina". For its conduct and work after the
1980 Irpinia earthquake the battalion was awarded a Bronze Medal of Army Valor, which was affixed to the battalion's flag and is depicted on the battalion's coats of arms.
Recent times On 31 May 1991 the
Mechanized Brigade "Trieste" was disbanded and the next day most of the units of the brigade, including the 66th Mechanized Infantry Battalion "Valtellina", joined the
Motorized Brigade "Friuli", which was renamed on that date Mechanized Brigade "Friuli". In 1992 the battalion was deployed for
Operation Sicilian Vespers in
Sicily. On 6 September 1993 the 66th Mechanized Infantry Battalion "Valtellina" lost its autonomy and the next day the battalion entered the reformed 66th Infantry Regiment "Trieste" as I Mechanized Battalion. The regiment not only became the custodian of the flag and traditions of the 66th Infantry Regiment "Trieste", but also of the traditions of the "Trieste" brigades and the "Trieste" division. From August 1993 to March 1994, the regiment participated in
United Nations Operation in Somalia II in
Somalia. In the following years the regiment was repeatedly deployed in the Balkans. In 2000 the regiment was reorganized as an
airmobile infantry unit and renamed 66th Airmobile Infantry Regiment "Trieste". In 2004 the regiment was deployed to
Nasiriyah in
Iraq, where it fought a heavy battle with
Iraqi insurgents on 7 and 8 September 2004. For its conduct in Iraq the regiment was awarded a Silver Medal of Army Valor. In 2008 the regiment was deployed to
Herat Province in
Afghanistan as part of Italy's contribution to
NATO's
International Security Assistance Force. During the regiment's stay in Herat its troops repeatedly engaged
Taliban forces in combat, for which the regiment was awarded Gold Medal of Army Valor. == Organization ==