A fascist paramilitary is a fighting force - whether armed, unarmed, or merely symbolic - that is independent of regular military command and is established for the defence and advancement of a movement that adheres to the radical nationalist ideology of fascism.
While many of the Blackshirts were former members of the Arditi who had fought in World War I or the Fascio of the immediate post-war years, the most direct inspiration for the first fascist paramilitary was Giuseppe Garibaldi's Redshirts.
A number of other fascist movements established paramilitaries modeled after the Italian original, most notably Nazism with its racialist view and its Sturmabteilung and Schutzstaffel.
Likewise, the combat wing of the Nazi Schutzstaffel, the Waffen-SS, fought in many major battles of World War II.
In an act of desperation, the Nazis deployed remnants of the Hitler Youth and Sturmabteilung against the Red Army in the Battle of Berlin.