On July 10, 1943, the Anglo-American forces landed in Sicily in order to bring the final blow to a Reich in increasing difficulty. The fascist regime, already in crisis for the numerous defeats he had suffered, was filed by those who had allowed its official establishment. The king, with the support of all moderate components of the regime (industrialists, military chiefs, hierarchies of the monarchical-conservative wing) and some members of the pre-fascist political world, tried to carry Italy out from an almost lost war and to save his institutional role. During a meeting of the Fascist Grand Council, held between 24th and 25th July 1943, the members of the party decided the end of the political power of the Duce, arrested immediately after his resignation as prime minister. At the head of government was appointed the former army commander, Marshal Pietro Badoglio.
The jubilation for this news didn't last so long. At the time Italy was still formally at war with the Allies, only after one month the secret meetings lead to a surrender pact, signed on the 3rd of September 1943 and announced on September 8. What followed was chaos.
The king, claiming ridiculous reasons such as to preserve Rome from Allies' attacks, fled to Brindisi, putting himself under the protection of the Anglo-Americans just arrived in Puglia; the army, without orders from the commander in chief Badoglio, was confronted as enemies by the old Germans allies, which came down in force to occupy the peninsula. Many Italian soldiers were killed and about six hundred thousand were made prisoners by Nazist troops during the days that followed the armistice. On September 12 a German commando freed Mussolini from his prison on the Gran Sasso Mountain (Abruzzo). After few days the recently deposed Duce re-founded the Fascist Party, establishing the "Italian Social Republic", with its capital at Salo' on Lake Garda, in the north of Italy, allied with the Germans.
With the Anglo-American blocked along the German defensive line, named Gustav, intersecting the peninsula from Gaeta, in southern Lazio, to the mouth of the river Sangro, in Abruzzo, Italy began to face the worst day of the Second World War.
Already from the 8th of September in the part of Italy occupied by Nazist troop people started to form groups to resist to the German invasion.
The rows of these formations, not yet organized, were characterized by people from different social and political backgrounds: communists, liberals, Catholics, anti-fascists of the first hour, people who believed that liberation from the Germans were coming, young men escaping the leverage imposed by the Social Republic. The formalization of the movement, under the auspices of the new born National Liberation Committee (formed by the Communist Party, the Socialist Party of Proletarian Unity, from newborns Christian Democrats, Liberal Democrats and Labour Democracy, by the newly formed Action Party), didn't give immediately to the groups holed up in the mountains the organization that they needed. The limited availability of weapons, together with the lack of logistical support provided by an organized network of contacts with the population, as it had been developed later, made the winter of 1943 particularly hard for those who had decided to pursue the partisan's struggle.
The subsequent organization into brigades, named according to the preponderance of their political orientation, and the arrival in some areas of good field commanders (for example Aligi Barducci, nicknamed "Potente", on the mountains around Florence) led to an increase in the military weight of the partisans, engaged in a war against Nazi occupation forces and in a real civil war against troops loyal to Mussolini, whose main task was precisely to hunt down and fight partisans. In continuing to the Allied advance to the north, on April 24, 1944, following the initiative of the Communist Party secretary Palmiro Togliatti, convinced of the priority of the liberation of Italy by the Germans against the need to set aside the monarchy in favor of the republic, the first government of national unity was formed: composed by the CLN's members, chaired by Badoglio and allied with the Anglo-Americans.
In June 1944, with the liberation of Rome, the Lieutenant-General of the kingdom was taken over by Umberto II, while General Badoglio resigns as head of government, in favour of a new national unity government, a direct offshoot of the National Liberation Committee, chaired by Ivanoe Bonomi.
Past the hard winter between 1943 and 1944, subsequently to the achievement of a greater internal organization and logistics, and the enlargement of their ranks with the arrival of an increasing number of draft dodgers in escape from the numerous calls of the army of Salo, the partisan's groups assumed ever greater weight in the fight against the occupying Germans. With the advance of the allied front guerrilla attacks conducted by partisans' brigades became more and more decisive, leading to some deals with the Anglo-Americans to enter first and free major cities like Florence.
After the liberation of the Tuscan capital (August 11, 1944) the local partisan brigades disbanded; their effects still eager to fight against the nazi-fascists, and not prevented by the immediate need to work for themselves and their family, joined the newborn Italian army commanded by the CLN and sided with allies on the difficult front of the Gothic Line (a series of fortifications and troop concentrations located along the Tuscan-Emilian Apennines from the Tyrrhenian to the Adriatic Sea).
The loss of importance of the southern European front for the advance towards Germany, combined with the difficulty of breaking the German defensive line, brought a halt along the Gothic Line. Meanwhile, the partisan groups of northern Italy continued their incessant action of attrition against the fascists and Nazis, despite the latter's bloody reprisals against the local population.
Emblematic was the case of Marzabotto village, located in the Appenins near the city of Bologna, where, between September 29 and October 5, 1944, the Germans killed in retaliation 1836 people. The breaching of the Gothic Line on river Sarno, near Rimini, and along the way that leads to Bologna, finally opened the field to the advancing of the Italian and allies' armies. In the spring of 1945, the partisan groups formed by about two hundred thousand headcount survived to the numerous raids and attacks by Germans and fascists during the harsh winter '44-'45, proclaimed the general insurrection that led to the liberation of Milan on April 25, 1945, the day of the final withdrawal of the German contingent and the defeat of the fascist troops of Salo'.