British historians usually write that Jerusalem was conquered during WW1 by British forces, but they often "forget" to remember that Great Britain received help from some military units of France and Italy. Of course this help -from the military point of view- was secundary and of little importance in the 1917 conquest, but it is worth to be remembered.
After 673 years the city "holy" to 3 religion followers (Christians, Jews and Moslems) returned to Christian rule in 1917 (and remained for 30 years under British control, until 1948).
The Italian government sent -in June 1917- the "Corpo di Spedizione Italiano in Palestina e Sinai" (Italian Expeditionary Force in Palestine and Sinai) to the area, where he fought for the conquest of Jerusalem from summer 1917 (and remained there until 1919; but some units left Palestine in 1921). It was initially made by nearly four hundred "Bersaglieri" and one hundred "Carabinieri" with their officials. They were under the orders of lieutenant colonel Francesco D'Agostino (http://www.tuttostoria.net/storia-contemporanea.aspx?code=329).
On November 7, 1917, General Allenby ordered the offensive on Gaza. A company of the Italian Detachment also took part in the "Third Battle of Gaza" framed in the "XX Composite Force" together with the Imperial Service Cavalry, the 20th Indian Infantry Brigade and six companies of the French contingent. The Italians valiantly defended the salient of Khan Yunis. The Turkish-German forces broke up, withdrew hastily, leaving Jerusalem to the Allies.
On December 6, a unit made up of twenty-five Bersaglieri, twenty-five Carabinieri and the two respective officers left for the Holy City, where Allenby dismounted from his horse out of respect for the place and entered on foot on the morning of 11 December accompanied by the Bersaglieri commander D'Agostino (in the meantime promoted to lieutenant colonel) and by the French counterpart De Piépape. In the holy city the royal Carabinieri were employed in the military police and guard services and the Bersaglieri controlled the railway Jerusalem-Giaffa until 1919.
Indeed in the famous photo of the general Edmund Allenby entering on foot inside Jeruralem on December 11, 1917 (see the following "Illustration" magazine first page), it is possible to see that he was followed by the French (colonel De Piepape) and Italian (lieutenat-colonel D'Agostino, with the typical bersaglieri hat) officials, representing all the troops that conquered the "holy" city.
Allenby later declared that:
....I entered the city (of Jerusalem) officially at noon, 11 December, with a few of my staff, the commanders of the French and Italian detachments, the heads of the political missions, and the Military Attaches of France, Italy, and America... The procession was all afoot, and at Jaffa gate I was received by the guards representing England, Scotland, Ireland, Wales, Australia, New Zealand, India, France and Italy. The population received me well...
In Palestine remained only a nucleus of Carabinieri on foot that took the name of "Italian Carabinieri detachment of Jerusalem", which from August 1919 to February 1921 carried out military police services, on guard at the Italian consulate, on guard of honor at the Holy Sepulcher and did courier activity between Egypt, Palestine and Syria.
On March first, 1921 the unit was repatriated and dissolved, ending five years of Italian troops presence in Palestine and Jerusalem.
Photo showing the Italian D'Agostino standing to the left of Allenby, when entered in Jerusalem
Finally, I want to add the translation of excerpts from an interesting article in italian, written by Benjamin Kedar and titled "Il distaccamento italiano in Palestina (1917-1919)" (if interested, read the full article at page 137 of the italian website http://www.societaitalianastoriamilitare.org/quaderni/Italy%20on%20the%20Rimland%20%20TOMO%20II.pdf):
THE ITALIAN DETACHMENT IN PALESTINE (1917-1919)
At noon on 11 December 1917, two days after the surrender of Jerusalem, General Sir Edmund Allenby officially entered the city going through the Jaffa Gate. «A representation of the troops in Palestine was lined up next to the Gate ”, this is what British official history reports on the First World War in Egypt and Palestine. "Out of the Porta were lined up on the right 50 guards of honor of the various English corps and on the left another 50 Australians and New Zealanders; inside 20 French on the right and 20 Italians on the left. All lined up, both inside and outside the door, facing each other the others ». As is well known, out of respect Allenby walked through the Gate on foot, side by side by the commanders of the French and Italian contingents, on the right Colonel Léonce Philpin de Piépape and on the left lieutenant colonel Francesco D'Agostino. Having gone up to the Citadel, the general took from his pocket the proclamation that had been telegraphed to him by his government and read it first in English, and then in French, Arabic, Hebrew, Greek, Russian and Italian.
Who were these Italian soldiers who are designated in the British Brief Record as "Italian detachment in Palestine"? Why were they there?
The Italian participation in the Allied operations in the Middle East arose from the reaction of the Italian Foreign Minister Sidney Sonnino against the exclusion of Italy from the expedition to Palestine decided by the Allies (in view of the division of the Middle East between France and Great Britain, secretly decided ten months earlier by Sykes and Picot).
On April 4, 1917 the British Foreign Office accepted the offer of an Italian contingent, presented on March 17 by the italian ambassador in London, Imperiali, but on the condition that the participation was purely symbolic and in the order of a few hundred men.
As wrote in 1932 Gustavo Pesenti, second and last commander of the Italian troops in Palestine, in March 1917 Italy had set up an expeditionary force in Libya of considerable size, with 6 battalions between national and indigenous & auxiliary troops under construction in Italy, including 5 SAM L-S2 aircraft of the 118th squadron. However, the contingent that landed in Port Said on May 19 under the command of D'Agostino counted only 352 bersaglieri (11 officers) with 46 quadrupeds coming from Tripoli and 100 carabinieri from Napoli.
After a few weeks of machine-gun & shooting training, on June 13 the detachment was transferred to Rafah, then as now on the border between Egypt and Palestine, to check the railroad towards Dayr al Balah. The trenches dug in the sand did not allow adequate defense to them and furthermore were also infested - as Pesenti wrote- with "indiscreet animals". Many soldiers fell ill: in July the daily average of patients was 2.5%; in August the proportions increased 8%, and 25 soldiers were sent back to Italy.
In early September - when Allenby was preparing for the "Third Battle of Gaza", which paved the way for the occupation of Jaffa and Jerusalem - the Italian detachment and six French units were framed in the XX Composite Force (under general Watson orders) along with an Indian brigade and a West Indian battalion: they were about 3,000 men from three continents.
According to Pesenti, the French contingent was not involved in any combat: this was due to the refusal of the French commander to be placed alongside Indian troops; the British command therefore considered withdrawing the Italian troops as well, but that did not happen because Watson, enthusiastic about the Bersaglieri, made his superiors change their opinion.
At the start of the Third Battle of Gaza (31 October) the Composite Force was deployed to the right of the XXI British Corps, connecting it with the XX Corps advancing on Beersheba. On the evening of the 31st Beersheba fell. On November 6, when the British advanced north of Beersheba, the Composite Force was in the same position facing the Turkish entrenched line of Atawine.
Then on November 7, the 21st Corps took Gaza and moved north of the area where it is today located the city of Ashdod. According to the aforementioned Brief Record on November 8 and in the following days the Composite Force participated in the taking of positions in Atawine and in the advance north of Gaza. The Italians successfully defended the salient of Khan Yunis from a counterattack.
On December 7, 25 Bersaglieri and 25 Carabinieri left for Jerusalem and four days later, as we have read, they participated at Allenby’s official entrance. Subsequently Italians, English and French provided the guard to the "Church of the Holy Sepulcher". In mid-December the Italian detachment was in Bayt Hanun, north of Gaza.
Meanwhile, Italian citizens residing in Egypt, in particular in Alexandria, had been called up to form a special company of "Palestine Hunters" ('Cacciatori di Palestina') that was created on December 10, 1917 in Port Said with 140 soldiers and 5 officers (including the commander, captain of the Bersaglieri Felice Mercuri). Later, on May 23, 1918 a platoon of 4 non-commissioned officers and 26 Carabinieri arrived from Napoli.
Additionally, from February 26, 1918 the Italian Expeditionary Force -now made of nearly one thousand soldiers with their officials- was also stationed at "Junction Station" (Wadi Sarar/Nahal Soreq station, in the Jaffa-Jerusalem railway) and carried out control tasks and surveillance in Jaffa and other nearby territories.
In July 1918, Allenby received the order of sending 2 of his divisions to France: he requested to replace them with Italians. Italian Prime Minister Sonnino was in favor, but Cadorna's successor, general Armando Diaz, declared that he could grant a maximum of 2 battalions and so the president of the Italian Council (Orlando) rejected the British request. Instead of two Italian divisions, to Allenby arrived two Indian divisions.
Therefore, it happened that in late 1918, when Allenby was about to launch the decisive offensive that led to the conquest of northern Palestine and Syria, the Italian detachment was left behind as part of the reserve: the Bersaglieri in Jaffa, most of the Carabinieri and "Cacciatori" in Lydda, and a platoon of Carabinieri in Jerusalem. Only Pesenti and the Italian military attaché, Major Balbo Bertone of Sambuy, were authorized to accompany Allenby on the fast advance on Damascus and Aleppo.
