Raid on Porto Buso: Difference between revisions

| combatant2 = {{flagflagicon|Kingdom of Italy}} [[Kingdom of Italy|Italy]]

| territory = Porto Buso and Grado captured by Italy

On 3 May 20151915, as a result of the [[Treaty of London (1915)|Treaty of London]], signed in secrecy on 26 April, the Italy's government changed sides and lined up with the [[Entente Cordiale]] and [[Russian Empire|Russia]], breaking their 33-year -old ties with the [[Triple Alliance (1882)|Triple Alliance]]. By that time, the German Empire and Austria-Hungary had been at war with Russia and the western powers since August 1914.<ref>{{Cite book|last=Nicolle|first=David|url=https://books.google.com.ar/books?id=SZoeDAAAQBAJ&pg=PA4&dq=3+May+1915+Italy&hlpg=en&sa=X&ved=0ahUKEwiH-NOMhovoAhWhLLkGHUNFAwkQ6AEIMjAB#v=onepage&q=3%20May%201915%20Italy&f=falsePA4|title=The Italian Army of World War I|date=|publisher=Bloomsbury Publishing|year=2012|isbn=978-1-78200-752-4|location=|pages=4|language=en}}</ref> The relationship between Italy and their former allies had already stranded since the beginning of the war, when the Italian government declared neutrality on the basis that the alliance was defensive in nature, and that Austria-Hungary had declared war on [[Serbia during World War I|Serbia]] without any official notification to them. In the following months, Italian diplomacy also tried to exert concessions from the [[Central Powers]], specially in the Adriatic region, to no avail.<ref>{{Cite book|last=United States Congress Senate|first=Committee on Foreign Relations|url=https://books.google.com.ar/books?id=ewpkYGRnWmkC&pg=PA190&dq=%22to+be+an+element+and+a+guarantee+of+peace%22&hlpg=en&sa=X&ved=0ahUKEwjRyv3bjovoAhWzK7kGHbMABLYQ6AEIKTAA#v=onepage&q=%22to%20be%20an%20element%20and%20a%20guarantee%20of%20peace%22&f=falsePA190|title=Termination of Treaties: The Constitutional Allocation of Power : Materials|date=1979|publisher=U.S. Government Printing Office|year=|isbn=|location=Washington DC|pages=191-92191–92|language=en}}</ref>

In a 4 January letter to the naval commander of the naval base of [[Venice]], the Chief of Staff of the Italian Navy, Vice Admiral [[Paolo Thaon di Revel]], devised an offensive strategy in the event of an Italian intervention in the Adriatic on the side of the Entente, when the destroyers and torpedo boats were to be major players. The letter made specific mention ofmentioned a possible attack on the Austro-Hungarian jetty and naval detachment at Porto Buso. The small island of Porto Buso is located in the mouth of the river [[Ausa (Udine)|Ausa]], and was at the time the southernmost border post of the Austro-Hungarian Empire. When it became obvious by mid-May that Italy would join the western Allies, the customs outpost was reinforced by a small garrison of soldiers from the Imperial Army's coastal defence, along with a signals detachment from the Austro-Hungarian Navy. Italian intelligence reports gave the impression that Porto Buso had received heavy machine guns and cannons to counter a possible Italian assault by sea.<ref> Rizza 2015, p. 71</ref>

When it became obvious by mid-May that Italy would join the [[Allies of World War I|Entente]], the customs outpost was reinforced by soldiers from the Imperial Army's coastal defence, along with a signals detachment from the Austro-Hungarian Navy. Italian intelligence reports gave the impression that Porto Buso had received heavy machine guns and artillery to counter a possible Italian assault by sea.<ref> Rizza 2015, p. 71</ref> The border post was actually the home of 69 servicemen and another 17 were scattered along other islands in the lagoon.<ref name=":2" /> The Italian goal was to clear the Austro-Hungarian presence across the northwest Adriatic coast in order to allow the Italian Navy support to their troops on the groundarmy. The move was also intended to deny the enemy the use of bases for their small torpedo units. On 25 April 1915, the task was assigned to the Sardegna Division, a flotilla of destroyers based at Venice.<ref> Rizza 2015, p. 71</ref>

The commander of the Sardegna Division, Admiral Giovanni Patris, codenamed the destroyer operation in the upper Adriatic "Missione A" (Mission A). The plan devised the deployment of four destroyers around the island of [[Grado, Friuli-Venezia Giulia|Grado]]. The [[Soldato-class destroyer|Soldato-class]] destroyers ''Bersagliere'' and ''Artigliere'' were ordered to shell Austro-Hungarian positions and naval assets around the town of Grado itself, while the [[Nembo-class destroyer|Nembo-class]] ''Zeffiro'', under the command of Captain Arturo Ciano, was in charge of the attack on Porto Buso. Another Soldato-class destroyer, ''CorraziereCorazziere'', was to sweep an area south of the lagoon in order to prevent any Austro-Hungarian interference. A secondary target was the telegraph cable connecting Grado with Cittanova.<ref> Rizza 2015, p. 71</ref>

At 02:00 &nbsp;am local time, ''Zeffiro'' passed through a channel southeast of Porto Buso unseen, at a 345° course, and stopping at 500 mt from the Austro-Hungarian wharf. The Italian destroyeddestroyer launched a torpedo, but it became stuck in the muddy bottom. The device was later recovered by Italian divers. Ciano immediatlyimmediately ordered Zeffiro's 76 mm guns to open fire on the watch towerwatchtower and the jetty, hitting the outpost, several customcustoms motorboats, and other small craft at anchor with 169 rounds. The Italian reports said that the barracks were repeatedly hit and that a number of small vessels were set on fire. The Austro-Hungarian garrison was taken by surprise, most of them in their sleep. A great number of personnel gathered on one of the sides of the jetty weaving a white flag.<ref> Rizza 2015, p. 72-73</ref>

According to Austro-Hungarian reports, particularly that of Oswald Steiger, commander of the Imperial coastal defences in the upper Adriatic, a column of smoke was spotted by the sentry Amandus Hummar, who reported two Italian destroyers approaching from the mouth of the [[Tagliamento|Tagliamento river]]. Mareth gave orders to abandon the outpost by sea. A motorboat with two staff petty officers aboard received a direct hit from ''Zeffiro''<ref name=":0">{{Cite book|last=Jung|first=Peter|title=La grande guerra nell'alto Adriatico. La difesa austro-ungarica del golfo di Trieste 1915-1918|publisher=LEG Edizioni|year=2013|isbn=8861021859978-8861021853|location=Gorizia|pages=16-1716–17}}</ref> and sank,<ref name=":1">Jung (2013), p. 18</ref> while a whaler evacuating ten customcustoms personnel and soldiers capsized; only three of the passengers managed to survive. Another four Austro-Hungarian servicemen were killed in action. When Lieutenaunt Mareth realised that any resistance would be futile, he stopped the withdrawal attempt and raised the white flag.<ref name=":0" /> Only six men were able to slip away to Grado, crawling through shallows and swamps. The 17 men manning observation postposts at the nearby islands also escaped Italian captivity.<ref name=":2">{{Cite web|url=http://www.betasom.it/forum/index.php?/topic/32636-prima-azione-della-r-marina/|title=Prima Azione Della R. Marina|website=Betasom -– XI Gruppo Sommergibili Atlantici|date=14 February 2010 |language=en-US|access-date=2020-03-26}}</ref><ref>{{Cite web|url=https://ilpiccolo.gelocal.it/tempo-libero/2015/05/15/news/e-l-italia-attacco-porto-buso-la-notte-del-24-maggio-1915-1.11426656|title=Quella notte l’Italial'Italia attaccò Porto Buso: era il 24 maggio 1915|date=2015-05-15|website=Il Piccolo|language=it-IT|access-date=2020-03-26}}</ref> Picked up by ''Zeffiro'''s cutter, Lieutenant Mareth formally surrendersurrendered to Captain Ciano, givengiving up his sabre and his revolver. The lukewarm attitude of Lieutenant Mareth, a Hungarian, was later criticised by Admiral Alfred von KudelkaKoudelka, commander of the naval sector of [[Trieste]] at the time.<ref name=":1" />

''Zeffiro'' arrived in Venice with 48 prisoners onboard, one of them seriously wounded. The local population was astonished when they realised that most of the captives were [[Friuli]]an-speaking men.<ref>{{Cite web|url=https://www.ilfriuli.it/articolo/cultura/i-primi-prigionieri-degli-italiani-furono-friulani/6/143269|title=I primi prigionieri degli italiani furono... friulani {{!}} Il Friuli|website=www.ilfriuli.it|date=18 May 2015 |language=it|access-date=2020-03-26}}</ref> Moreover, one of the Austro-HungariansHungarian servicemen killed at Porto Buso was the cook Eugenio Sandrigo, from Grado, who became the first ethnic Italian to die in the war.<ref>{{Cite web|url=https://www.ilgazzettino.it/pay/belluno_pay/alfabeto_numeri_grande_guerra-1145497.html|title=Alfabeto e numeri della Grande guerra|website=www.ilgazzettino.it|date=16 July 2015 |language=it|access-date=2020-03-26}}</ref>

The other destroyers of the Sardegna Division did not enjoy the same success. ''Corazziere'' not only did not find any enemy unit, but she was also unable to cut the telegraph cable to isolate Grado. In the same way, ''Bersagliere'' and ''Artigliere'' searched in vain for valuable targets at Grado. The destroyers' commanders renounced to bombard the town in order to avoid civilian casualties.<ref> Rizza 2015, p. 71</ref> The Italian sortie did not prevent the free movement of the Austro-Hungarian Fleet that, departing from [[Pula]] and [[Šibenik|Sibenik]], bombarded several Italian ports and facilities further south.<ref> Rizza 2015, p. 74</ref>

On 25 May, an Italian marines' detachment landed in Porto Buso and took the facilities over. The marines rounded up some stragglers and seized two abandoned motorboats untouched by ''Zeffiro''<nowiki/>'s shelling. The next day Grado was captured by a company of [[Bersaglieri]] after being vacated by the remaining Austro-Hungarian troops.<ref> Rizza 2015, p. 75</ref>