On 21 August 1964, the historic leader of the Italian Communist Party, Palmiro Togliatti died of cerebral haemorrhage[2] while vacationing with his companion Nilde Iotti in Yalta, then in the Soviet Union.

In 1965, the SIFAR intelligence agency was transformed into the SID following an aborted coup d'état, Piano Solo, which was to give power to the Carabinieri, then headed by general De Lorenzo.

This movement was characterized by such heterogeneous events as revolts by jobless farm workers (Avola, Battipaglia 1969), occupations of Universities by students, social unrest in the large Northern factories (1969 autunno caldo, hot autumn).

Mario Capanna, associated with the New Left, was one of the figures of the student movement, along with the members of Potere Operaio and Autonomia Operaia such as (Antonio Negri, Oreste Scalzone, Franco Piperno and of Lotta Continua such as Adriano Sofri.

The result shocked the PSI's leadership, causing the sudden sinking of the social-democratic federation, and an alternance of provisional retirements by the government, firstly led by lifetime senator Giovanni Leone and then, through two political crisis, by DC's secretary Mariano Rumor.

Unsuccessfully trying to recover its lost leftist electors, the PSI returned to the alliance with the PCI for the regional elections of 1970, so causing another crisis and a new change of premiership, then led by Emilio Colombo, but the government coalition had continuous problems of instability.