The Invasion of Yugoslavia
Between 6–18 April 1941, the Italian 2nd Army and 9th Army committed a total of 22 divisions to the invasion of Yugoslavia, comprising around 300,000 troops.
The Italian 2nd Army (Italian: 2° Armata) was commanded by General designato d-Armata (General Vittorio Ambrosio and consisted of one fast (Italian: celere) corps (Celere Corps), one motorized corps (Motorized Corps) and three infantry corps (V Corps, VI Corps, and XI Corps), and was assembled in northeastern Italy, attacking from Istria and the Julian March along the border with Slovenia and Croatia. The 2nd Army was supported by a motorized engineer regiment including three bridging battalions, a chemical battalion, fifteen territorial battalions, and two garrison battalions.
V Corps support units included three motorized artillery regiments comprising thirteen battalions, four machine gun battalions (two motorized and two pack animal), three Blackshirt legions of battalion size, a motorized anti-aircraft battalion, a sapper assault battalion and a road construction battalion. VI Corps included four motorized artillery regiments with a total of sixteen battalions, two machine gun battalions (one motorized, one pack animal) and a motorized anti-aircraft regiment. XI Corps included one motorized artillery regiment comprising four battalions, three machine gun battalions (one motorized, one pack animal and one static), and six Blackshirt legions of battalion size. The Motorized Corps was supported by a motorized artillery regiment consisting of three battalions, and an motorized engineer battalion.
In Albania, the elements of the Italian 9th Army (Italian: 9° Armata) that were involved in the campaign were commanded by Generale d’Armata – General Alessandro Pirzio Biroli, and consisted of two infantry corps and some sector troops assembled in northern Albania.
XIV Corps was supported by a cavalry regiment, three Border Guard battalions, a Finance Guard battalion and two military police (Carabinieri Reali) battalions. The XVII Corps included the Diamanti Blackshirt group which incorporated six Blackshirt regiments comprising two battalions each, the Albanian-raised Skanderbeg Blackshirt regiment of two battalions, another Blackshirt regiment of two battalions, a cavalry regiment, a Bersaglieri motorcycle battalion, three Border Guard battalions, one Finance Guard battalion, a motorized artillery regiment of three battalions, a military police battalion, and a tank company equipped with Fiat M13/40 light tanks. The Librazhd Sector included a motorized artillery regiment of four battalions, a bicycle-mounted Bersaglieri regiment, a cavalry regiment, the Biscaccianti Blackshirt group which incorporated two Blackshirt regiments with a total of five battalions, the regimental-sized Agostini Blackshirt Forest Militia, and the Briscotto group, a regimental-sized formation consisting of one Alpini battalion and two Finance Guard battalions.
The Zara garrison numbered about 9,000 men under the overall command of Generale di Brigata (Brigadier) Emilio Giglioli. The garrison consisted of two main groupings and an assortment of supporting units. The two main groupings were the regimental-sized Fronte a Terra (Land Front), which comprised three static machine gun battalions and a bicycle-mounted Bersaglieri battalion, and the battalion-strength Fronte a Mare (Sea Front), which consisted of two machine gun companies, an anti-aircraft battery, a coastal artillery battery and a naval artillery battery. Supporting units consisted of an artillery regiment of three battalions, two independent artillery battalions, a machine gun battalion, a motorized anti-aircraft battalion (less one battery), an engineer battalion, a company of Blackshirts, and a company of L3/35 tankettes.
In the opening days of the invasion, Italian forces on the Slovene border carried out major actions in the Sava valley and in the Kastav area, capturing some Yugoslav positions on Mount Peč on April 7, Kranjska Gora, Zavratec and Godz on April 8, Kastav, the source of the Rječina river, Kalce and Logatec on April 9, and repelling on April 8 a Yugoslav attack in the Cerkno Hills. On April 11, the 2nd Army launched its offensive, capturing Ljubljana, Sussak and Kraljevica on the same day. On 12 April the 133rd Armoured Division Littorio and the 52nd Infantry Division Torino took Senj, and on 13 April they occupied Otočac and Gradac, while Italian naval forces occupied several Dalmatian islands. A scheduled Yugoslav attack against the Italian enclave of Zara did not materialize, and the city garrison’s troops started to advance until they met the “Torino” Division near Knin, which was taken on the same day. Split and Sibenik were taken on April 15 and 16, respectively, and on 17 April the Motorized Corps took Dubrovnik, after covering 750 kilometers in six days.
After repelling the Yugoslav offensive in Albania, the 18th Infantry Division Messina took Cetinje, Dubrovnik and Kotor on 17 April, meeting with the Italian units of the Motorized Corps.
Between 11–13 April 1941, with German and Italian troops advancing on its rear areas, the Zetska Division was forced to retreat back to the Pronisat River by the Italian 131st Centauro Armoured Division, where it remained until the end of the campaign on 16 April. The Centauro Division then advanced upon the Yugoslav fleet base of Kotor in Montenegro, also occupying Cettinje and Podgorica.
Despite these losses, more than 70 Yugoslav aircraft escaped to Allied territory, mostly to Greece, but eight Dornier and Savoia Marchetti bombers set course for the USSR, with four making it safely. Several dozen of the escapee aircraft were destroyed in a devastating strafing attack by the Italian air force on Paramitia airfield in Greece, with only nine bombers and transports making it to Egypt. More than 300 operational, auxiliary and training aircraft were successfully captured by the Italians and passed on to the newly created Air Force of the Independent State of Croatia, Finland, Romania and Bulgaria.
The Italians captured most of the Yugoslav Navy (one of its four destroyers, the Ljubljana, had spent the campaign in dry-dock). However, another destroyer, the Zagreb, was blown up at Kotor by two of its officers to prevent capture and one of the British-built submarines and two MTBs succeeded in escaping to Alexandria in Egypt to continue to serve with the Allied cause. A fourth destroyer was captured while under construction in the Kotor shipyard, the Split, but the Regia Marina was not able to finish her before the armistice in 1943.
Thus, in less than two weeks, the Italian 2nd and 9th armies, with the support of their other Axis partners, notably Germany and to a lesser extent, Hungary, successfully invaded and controlled much of the Balkans, including Greece.