Catalysts of the Civil War
The war began after the Treaty of Rome was signed on August 5 between the Kingdom of Italy and the victorious Central Powers, ending the Italian front with Austria-Hungary and the African front with the Abyssinians and Tripolitanians in the Weltkrieg. The Treaty ended the state of Italy as it had existed since 1861, and replaced it with a devolution to the smaller monarchies and other states that had existed before the unification by the house of Savoy. These were Sardinia-Piedmont, Modena, Parma, Tuscany, the Papal States, and the Two Sicilies. These states would form a decentralized Italian Federation, with the Habsburg Grand Duke of Tuscany serving as the initial Head of the Federation. Lombardy and Venetia were to be occupied by Austria until an adequate local government could be formed. Austria-Hungary also deployed troops to the rest of occupied Italy, especially a sizable contingent that was stationed in Rome, in order to maintain control while the treaty came into effect. In the Horn of Africa, Abyssinia received Eritrea, and Somalia was granted to the British protectorate of Warsangali. Tripolitania and the Dodeconese islands were to be returned to the Ottoman Empire, which they had possessed until 1911.
Beginning of the Conflict
When the treaty was announced, nationalists, socialists, and republicans in Milan renounced the House of Savoy for betraying the nation, and declared a republic on August 7. Central and Northern Italy was in uproar, and Austrian and German garrisons struggled to maintain order against the underground republic. Popular uprisings occured across Italy, and sometimes mutinous army regiments split themselves against each other. The republican capital of Milan was swiftly overrun by the occupying Austrian forces, who were caught in the conflict. In Rome, Pope Benedict XV re-emerged from the Vatican to reclaim his nation, as the city and the surrounding areas stabilized because of the presence of Austrian soldiers and Catholic volunteers. In Napoli and the Mezzogiorno, also, mainly local militias with some Austrian support managed to keep the situation stable enough to contain most uprisings in the cities and countryside, though King Ferdinand III of Bourbon was advised to remain outside the country while the civil conflict was still ongoing by Vienna. Tuscany fell rapidly to the rebels, as there were few garrisons there. The republicans also secured most of Parma by the end of August, and soldiers returning from Venice and the South to their homes were quickly drafted once more into the service of any of the sides.
Vienna demanded on September 13 that Generalfeldmarschall von Hindenburg divert troops and supplies from the occupation of France to Central Italy. Berlin replied that there were no troops to spare. The Romagna fell to the Republicans by the end of September. The last Austrian garrison in Central Italy surrendered on September 29 in Perugia. All Austrian soldiers remaining in Central Italy were shot on sight by socialist and nationalist rebels. Meanwhile, in the northwest, nationalist forces began to organize themselves into more than just gangs and looters. Emilio de Bono was recruited by the republic to lead the Third Army, and began a push into Liguria against the collapsing Savoyard armies.
In a great coup for the republicans, General de Bono routed the Savoyard armies from Liguria, and King Emanuele Filiberto fled to Sardinia on November 2. Unfortunately for the rebel cause, the first disputes between "Red’’ and "White’’ republicans begin in early October, especially in Piedmont and Lombardy. At this point, sabotage began on both sides, as White forces destroy most of the factories in Piedmont and Liguria with help from local industrialists, before retreating eastward.
The continuing combined Republican offensive in Umbria was ground to a halt by late November, as Red and White troops refused to continue to fight together. White forces, including General de Bono, decamped to a temporary capital in Parma. Meanwhile, with the end of the assault on the Federation in Tuscany, the Socialists could devote greater resources to the attack on Emilia. The Battle of Parma began on December 6, and lasted three bloody weeks as the encircled Republicans were finally relieved by forces diverted from fighting the Austrians in Veneto. Ravenna at this time, however, was retaken by the Austrians by sea, who prepared for a joint offensive between their forces in Venice, Milan, and Ravenna to cut off the Republicans from the Adriatic and each other.
The imminent risk of a full Austrian intervention motivates the first diplomatic overtures between the Republicans and Austrians. Both sides wished to prevent a fully socialist Italy, but once these plans were leaked, were fuel to the fire and irreversibly divided the Republicans in Right- and Left-Wing factions. On Christmas Day of 1919, the Socialist Republic of Italy was declared in Torino. The Commune of France, still in the midst of its own civil war against the Nice junta, offered only limited support to their Syndicalist comrades, consisting mostly of a few advisers, both political and military,
War in the Marche
Meanwhile, Socialist preparations for an attack began. The Socialist leadership was eager to test their new Red Guards, formed out of the ad-hoc socialist militias and trained by former Italian officers and French advisors. As the front against the newly-declared Whites stabilized in the north, Red Guards were dispatched to reinforce assembling militias in Tuscany for an attack (Operation Garibaldi) to take Rome and crush the Papal State before foreign volunteers could arrive in Rome. Austrian soldiers and drafted Papal Zouaves had had time to prepare for the attack, however, and had prepared trenches and forward bases along a defensive line stretching from Rome through Ascoli Pisceno to Ancona. When the attack came on January 15, it was accompanied by a a terrible storm that blinded the defenders and allowed the Socialists to break the lines disastrously at Ascoli Piscena, allowing Ancona to fall by the end of January. The defenders attempted to swing the line westward to counter the Socialist invasion into the Two Sicilies. They now were granted a reprieve, as Sicilian soldiers, returned from the war and called back into their units by the Sicilian government, stopped the Socialists just south of the border and reinforced the Austro-Papal lines in Rome. Socialists tried to continue Operation Garibaldi with a naval assault on Civitavecchia, Rome's port, but were driven off with heavy losses. All major socialist offenses in the south halted by March 3. King Ferdinand de Bourbon and the royal family arrived in Napoli under guard and were installed in the Palazzo Reale.
After the failure of Operation Garibaldi, the socialists attempted no further major offensives, contenting themselves with inching away at the Republicans in Romagna. The Austrians, meanwhile, moved on the Republicans along the coast and in the Alps, gaining some ground. However, at this time the effort required to sustain the various Austrian occupations in Serbia, Montenegro, Romania, Ukraine and Italy was beginning to break the Austro-Hungarian army. Small-scale warfare continued for a month and a half, while all sides prepared for the rumoured Socialist offensive. On May 18, it finally came. Tens of thousands of socialist militias and Red Guard began enormous attacks against the Republicans, driving them out of Piedmont, Romagna, and Emilia. On May 22 the Republican, Federation, and K.u.K. governments signed an armistice and limited pact against the Syndicalists at Treviso. The exact terms of diplomatic recognition and ties were to be decided after the Socialist Republic was defeated. Austo-Hungarian troops trained to the front from their positions in the Alps and Veneto, and managed to barely stop the advancing socialists at the "Miracle at the Po", by destroying several bridges with air and artillery strikes, effectively cutting off the SRI from Republican territory. No further offensives by either side would be undertaken.
Austria-Hungary and the Whites signed the Treaty of Trieste on October 4 1920, which stated that Austria would recognize the Republican government as the legitimate government of Italy north of the Po. However, this would have to remain under the framework of the Italian Federation. Thus, the Republic of Lombardy-Venetia was born, the Prime Minister of which was granted the title of Interim Head of the Council of the Italian Federation, taken from now-occupied Tuscany as a sop to White national pretensions. Large amounts of autonomy in Venetia satisfied many who simply wished for an end to the conflict, while retaining local rule. Both nations announced their friendship toward each other, and Austria pledged to support the Whites should the Socialists attack again. Crucially for later events in 1927, however, Austria made no specific pledge to protect the Mezzogiorno, while garrisons did remain in Rome, Naples, and Taranto at the time. This unstable arrangement would inevitably culminate in the War Scare of 1927, and later collapse of the Italian Federation. Concurrently, in northwestern Italy, the Nice Junta was defeated with participation of SRI and CoF troops in the offensive, in the first official joint operation between the two nations. Red Italian forces partake in small numbers in the final stages of the French Revolution in Savoy, but most are on the verge of mutiny and return to their often ruined homes.