The Seguro Obrero Massacre took place on September 5, 1938, in the midst of a heated three-way election campaign between the ultraconservative Gustavo Ross Santa María, the radical Popular Front's Pedro Aguirre Cerda, and the newly-formed Popular Alliance candidate, Carlos Ibáñez del Campo.

In the 1930s, the National Socialist Movement of Chile gained seats in Chile's parliament and attempted a coup d ' état that resulted in the Seguro Obrero massacre of 1938.

* 1938 – Chile: A group of youths affiliated with the fascist National Socialist Movement of Chile are assassinated in the Seguro Obrero massacre.

After this embarrassing incident, known as the Seguro Obrero massacre, Ibáñez decided to abandon the presidential campaign.

González von Marées organized a failed coup attempt on September 5, 1938, in which 58 young nacista members were shot to death by police, in what became known as the Seguro Obrero massacre.

For the presidential elections of 1938, he was the candidate of the Popular Front, and narrowly defeated conservative candidate Gustavo Ross, mostly because of the political backlash caused by the Seguro Obrero Massacre.

His role in the 1938 Seguro Obrero massacre has always been subject of controversy.