On this day in 1973, anti-communist snipers fired on a huge crowd of Peronists gathered at Ezeiza International Airport to witness the return of Juan Perón. At least thirteen were killed, and left-wing alliances to Peronism were severed.

Peronism is an Argentine political movement based on the ideas and legacy of Argentine military general and politician Juan Perón (1895 - 1974) and his wife Eva. Peronism was a popular third positionist political movement that had elements of left and right-wing political ideas.

On June 20th, 1973, Juan Perón was returning to Argentina after eighteen years of political exile in fascist Spain. A large crowd gathered to witness his return at Ezeiza International Airport; police estimated three and a half million people total were present.

At the time, an alliance of right-wing and left-wing movements existed within Peronism, with the Peronist Youth and the Montoneros exhibiting anti-capitalist politics. While the crowd was gathered at the airport, right-wing snipers began firing on the crowd, targeting the Peronist Youth and Montoneros, killing at least 13 people and injuring 365 more.

The Ezeiza massacre marked the end of the alliance of the left and right-wing Peronists which Perón had managed to forge. According to Hugo Moreno, "If [the general strike on] October 17th, 1945 may be considered as the founding act of Peronism...the June 20th, 1973 massacre marked the entrance on the scene of the late right-wing Peronism."