The Roman salute is a gesture that dates back to ancient Rome, and then was adopted by the French during the 18-19th century, United States during the 19-20th century and finally by the Fascists.
The Tennis Court Oath (French: Serment du jeu de paume) was a pivotal event during the first days of the French Revolution. The Oath was a pledge signed by 576 of the 577 members from the Third Estate who were locked out of a meeting of the Estates-General on 20 June 1789. They made a makeshift conference room inside a tennis court located in the Saint-Louis district of Versailles (commune), near the Palace of Versailles.
Students pledging allegiance to the American flag with the Bellamy salute
In Italy, Achille Starace, the Italian Fascist Party secretary, pushed for measures to make the use of the Roman salute generally compulsory, denouncing hand shaking as bourgeois. He further extolled the salute as “more hygienic, more aesthetic, and shorter.”
In Germany the salute, sporadically used by the National Socialist German Workers Party since 1923, then was enforced within the movement in 1926. Named the Hitler salute, it functioned both as an expression of commitment within the party and as a demonstrative statement to the outside world. However since it’s not Germanic, it did not go unchallenged, even within the movement. Hitler salute became compulsory for all public employees by Reich Minister of the Interior Wilhelm Frick on July 13, 1933.