The Union Interalliée was founded in 1917, at the time of the official entry of the United States into the war, just after the voluntary aviators from the La Fayette flight, who had come to increase the number of those who were fighting for the same cause on French soil.
The founders of the Union Interalliée (the Count of Beaumont, Paul Dupuy, the Count J. de Bryas, Arthur Meyer, MJ of Sillac) suggested establishing a place of welcome providing moral and material resources to the officers and personalities of the Allied nations, in order to develop the allied life that had just begun.
Thanks to the support they received from several statesmen, ambassadors and field marshals and the assistance from new collaborators (Count of Andigne, Bardac, du Breuil Saint-Germain, André Citroën, L. Dumontet, the Count of Fels, who created, along with the former, the directing committee, chaired by Vice Admiral Fournier), they founded the Union Interalliée in one of the most beautiful mansions in Paris, the hotel Henri de Rothschild, which had been generously offered to them.
In 1920 the Association, having set up a real estate company, acquired the building for the sum of 1 067 143 €.
The war having ended, the need for the Union Interalliée was apparent to everybody, as it was more necessary than ever to maintain harmony between the people who had fought together.Field Marshal Foch became President of the Cercle on 1st June 1920.
The work, begun in 1917, received an official consecration in 1920 :the public authorities recognized its importance in diplomatic relations between the allied nations.