The Trieste Mechanized Brigade was a mechanized brigade of the Italian Army. Its core units were mechanized Infantry battalions. The brigades headquarters was in the city of Bologna.
The Trieste brigade's history began in August 1862 when the Valtellina Infantry Brigade was raised. The brigade consisted of the 65th Infantry Regiment Valtellina and the 66th Infantry Regiment Valtellina. The brigade along with the Brescia Brigade formed the 5th Division of the Line in the Third Italian War of Independence, where it fought in the Battle of Custoza. Personnel from the brigade was dispatched to fight in the Italian colonial wars in Eritrea in 1887, Abyssinia in 1895 and Libya in 1911.
During World War I the brigade fought on the Italian Front as part of the 7th Division of the Line, which was part of the IV Army Corps. In spring 1915 the brigade moved to the Austrian border and saw its first combat during the First Battle of the Isonzo. By war's end the brigade had reached the city of Trento.
In 1926 the Italian army decided to change the structure of its divisions: instead of two brigades with two infantry regiments each the new divisions would consist of one brigade with three infantry regiments. Therefore, in the same year the Valtellina brigade was disbanded. The 65th regiment was transferred to VIII Infantry Brigade of the 8th Infantry Division Po, while the 66th regiment was transferred to XVI Infantry Brigade of the 16th Infantry Division Fossalta.
On 6 May 1937 the two regiments were re-united in the 8th Infantry Division Po, which was subsequently equip as an motorised division. The division also consisted of the 21st Artillery Regiment and in 1938 it added the 9th Bersaglieri Regiment, making it one of the few Italian divisions with three infantry regiments instead of the standard two infantry regiments. On 4 April 1939 the units was renamed as 101st Motorised Division Trieste. At the outbreak of World War II the division was one of the few fully motorised divisions of the army.
The division command and 21st Artillery Regiment were sent to Albania in fall 1940 to reinforce the Italian units in the Greco-Italian War. After German forces had conquered Greece in the Battle of Greece the division command and 21st Artillery Regiment returned to Italy. In August 1941 the division was sent to Libya where it formed with the 132 Armoured Division Ariete the Italian XX Motorised Corps. The Trieste immediately entered the frontline in the Siege of Tobruk. From Tobruk on the division participated in all Western Desert Campaign battles: Operation Crusader, Battle of Gazala, Battle of Bir Hakeim, First Battle of El Alamein. During the Second Battle of El Alamein the Trieste was virtually destroyed. After El Alamein the remnants of the division were reinforced with men and materiel from Italy and fought against the British Eighth Army in Tunisia until it surrendered to the Allies on 13 May 1943.
On 1 June 1950 the division was raised again as Trieste Motorised Infantry Division in the city of Bologna. The division was the only major unit under the VI Military Territorial Command and consisted of the 40th Infantry Regiment Bologna, 82nd Infantry Regiment Torino and the 21st Artillery Regiment. In 1951 the division was augmented with the 6th Armoured Cavalry Squadron "Lancieri di Aosta" and the 121st Artillery Regiment.
However, on 20 October 1954 the division was split in two formations: the Trieste Group with the 82nd Infantry Regiment Torino and one artillery group of the 21st Artillery Regiment and the Bologna Group with the 40th Infantry Regiment Bologna and one artillery group of the 21st Artillery Regiment. The 6th Armoured Cavalry Squadron passed to the VI Military Territorial Command. The 121st Artillery Regiment had already left the division on 5 June 1953 when the regiment became the 121st Heavy Anti-air Artillery Regiment. The Trieste Group moved from Bologna to its namesake city Trieste after it was returned to Italy on 26 October 1954.
In 1955 the army decided to assign the defence of Trieste to the Folgore Motorised Infantry Division. Therefore, the Trieste Group was disbanded on 15 September 1955 and its units passed to the Folgore, while on the same day the Bologna Group was elevated to division and was returned the name Trieste. In September 1956 the Trieste and the Friuli Motorised Infantry Division entered the newly raised VI Army Corps.
On 30 May 1960 the division received the XI armoured battalion and on 20 October of the same year the division was reduced to Trieste Infantry Brigade. The brigade was headquartered in Bologna and most of its units stationed in the surrounding region of Emilia-Romagna. By 1964 the structure of the brigade was:Trieste Infantry Brigade:
40h Infantry Regiment Bologna with three infantry battalions
XI Armoured Battalion with M26 Pershing
Trieste Field Artillery Group with M114 155/23 towed howitzers
Trieste Light Anti-Air Artillery Group with M1 40/56
Trieste Engineer Company
Trieste Signal Company
Trieste Light aeroplane section with L-21A Super Cub
In 1972 the VI Army Corps was disbanded and the brigade along with the Friuli came under the Tuscany-Emilian Military Region. In 1975 the Italian army undertook a major reorganisation: the regimental level was abolished and brigades took direct command of battalions, more units were mechanized and higher commands realigned to better defend Italy against a potential Warsaw Pact attack. Therefore, on 1 August 1975 the Trieste entered the Folgore Mechanized Division and changed its name to Trieste Mechanized Brigade. The 40th Infantry Regiment was disbanded and each of its three battalions became a newly independent battalion under direct control of the brigade. The brigades new composition was:Trieste Mechanized Brigade:
Trieste Command and Signal Battalion in Bologna
11th Tank Battalion M.O. Calzecchi in Ozzano dell'Emilia, with Leopard 1A2 main battle tanks
37th Mechanized Infantry Battalion Ravenna in Bologna with M113 armoured personnel carriers
40th Mechanized Infantry Battalion Bologna in Bologna with M113 armoured personnel carriers
66th Mechanized Infantry Battalion Valtellina in Forlì with M113 armoured personnel carriers
21st Artillery Group Romagna in Bologna, with M114 155mm towed howitzers
Trieste Logistic Battalion in Budrio
Trieste Anti-tank Company in Bologna
Trieste Engineer Company in Bologna
On 1 August 1986 the Army disbanded all its divisions and the Trieste passed to the 3rd Army Corps in Milan. As tensions between NATO and the Warsaw Pact eased the 40th Mechanized Infantry Battalion Bologna was disbanded on 16 December 1989.
After the end of the Cold War Italian Army began a draw-down of its forces: six brigades were disbanded in 1991 while the Trieste merged on 1 June 1991 with the Friuli Motorised Brigade. The new brigade was named Friuli Mechanized Brigade, but headquartered in Bologna in the HQ building of the Trieste brigade. Before the merger the 37th Mechanized Infantry Battalion Ravenna had disbanded on 28 February 1991 and its barracks in Bologna had been taken over by the 10th Bersaglieri Battalion Bezzecca of the disbanded Goito Mechanized Brigade on 1 March 1991.
In 1992 the Army decided to rename its battalions as regiments for historical reasons. When the 66th Mechanized Infantry Battalion Valtellina became the 66th Infantry Regiment in 1992 the army decided to not give the regiments its traditional name Valtellina, but to give the regiment the name of the dissolved brigade. Thus the 66th Infantry Regiment Trieste became the custodian of the history, traditions and honours of the Valtellina regiment, as well as the Trieste brigade and the Trieste division.