By 10 June 1940, Siena was transferred to Piedmont as part of the army reserve, and did not participate in Italian invasion of France. Fully mobilized in August 1940, the Sienadivision received orders to move to Albania in September 1940. By the start of Greco-Italian War On 28 October 1940, the division was deployed in the Delvinë-Konispol region as part of the Italian VIII Corps, covering the border from Mal Stugarë where it was adjacent to the 23rd Infantry Division Ferrara to the coast. Ordered to participate in the attack on the Greek city ofIoannina, the division failed to cross the Thyamis river until 6 November 1940 due to heavy Greek resistance. On 6 November 1940, the beachhead across the Thyamis was established, but the division immediately turned to a defensive stance because of the rapid pace of Greek forces build-up. On 14 December 1940, it repelled Greek probing attacks, but by 19 December was retreating with the main forces from the line from Himarë to Kallarat. It was able to stop the Greek advance just short of the valley of Shushicë, on the mountaintops of Mali i Çorajt to Horë-Vranisht. The fighting was bloody, with the infantry regiments of Siena down to the battalion strength. The 33rd Mountain Infantry Division Acqui came to the rescue on 24 December 1940, and by 26 December 1940 the Siena division was relieved from front line duties and sent to Berat to regroup. To plug the Greek breakthrough after the Capture of Klisura Pass, on 25 January 1941 the Siena division was assigned to the line from Qafa e Kiçokut - Monastery Hill north of Këlcyrë. It managed to stop the breakthrough, despite incessant Greek attacks. On 8 February 1941, the division was sent to reserve again. It participated in the Italian Spring Offensive on 19 March 1941 and in the Battle of Greece, capturing Këlcyrë on 14 April 1941. An order was given to Siena on 16 April 1941 to stop and to give way to the 47th Infantry Division Bari. After the fighting ended, Siena was first re-organized in the Osum valley and then sent to Peloponneseat the beginning of May 1941, forming garrisons in Corinth, Nemea, Argos and Nafplion. In late September 1941, the division was transferred to the eastern part of the island of Crete, joining the Italian XXVI Corps. On 18 April 1943, parts of Siena repelled an Allied landing attempt on the island of Koufonisia. The division remained in Crete until September 1943, when Italy surrendered to the Allies according to the Armistice of Cassibile and the division was disarmed by the Germans. In October 1943, about 2,000 men were killed when they were transported to the mainland as PoWs on the MS Sinfra, which was sunk by US and British planes. Another 2,670 men drowned in February 1944 on the SS Petrella, which was torpedoed by the British submarine HMS Sportsman.
