The Italian resistance movement was the Italian resistance groups who fought the occupying forces of Nazi Germany and the fascist collaborationists of the Italian Social Republic during the Second World War in Italy from 1943 to 1945. As a diverse anti-fascist movement and organisation, the Resistenza opposed Nazi Germany, as well as Nazi Germany's Italian puppet state regime, the Italian Social Republic, which the Germans created following the Nazi German invasion and military occupation of Italy by the Wehrmacht and the Waffen-SS from 8 September 1943 until 25 April 1945.

The Italian Socialist Party was a social-democratic and democratic-socialist political party in Italy, whose history stretched for longer than a century, making it one of the longest-living parties of the country. Founded in Genoa in 1892, the PSI was from the beginning a big tent of Italy's political left and socialism, ranging from the revolutionary socialism of Andrea Costa to the Marxist-inspired reformist socialism of Filippo Turati and the anarchism of Anna Kuliscioff. Under Turati's leadership, the party was a frequent ally of the Italian Republican Party and the Italian Radical Party at the parliamentary level, while lately entering in dialogue with the remnants of the Historical Left and the Liberal Union during Giovanni Giolitti's governments to ensure representation for the labour movement and the working class. In the 1900s and 1910s, the PSI achieved significant electoral success, becoming Italy's first party in 1919 and during the country's Biennio Rosso in 1921, when it was victim of violent paramilitary activities from the far right, and was not able to move the country in the revolutionary direction it wanted.