donald trump
US President Donald Trump (Image: AP/Alex Brandon)

On February 20, 1939, 20,000 Americans crammed into New York's fabled Madison Square Garden.

They weren't there to cheer the New York Rangers in their hunt for the Stanley Cup, or for Joe Louis to defend his heavyweight boxing crown. They had come to be part of a "Mass Demonstration for True Americanism", a self-proclaimed pro-American rally hosted by the German American Bund.

The Bund was an American Nazi organisation founded in 1936. Its forerunner was started three years earlier by Heinz Spanknöbel, a German Nazi, on the orders of Hitler's deputy, Rudolf Hess. In the vein of the infamous Nuremberg rallies, the spectacle was choreographed with American flags and swastika banners, uniformed storm troopers, martial music and Nazi salutes.