"Z" was a 1969 film directed by the Marxist director Costra-Gavras based on the Lambrakis affair in Greece in the Sixties. In the film, as the Greek military is linked to the murder of Lambrakis, the military reacts by overthrowing the civilian government in a coup d'etat.
In real life, the Lambrakis killing and the coup were not connected, but it was a good dramatic point.