In 1909 Seligmann bought the Palais de Sagan in Paris, which served as the showcase venue for large exhibitions and client visits.
Early notable clientele included Edmond James de Rothschild, the Stroganov family, Philip Sassoon, Benjamin Altman, William Randolph Hearst, J. P. Morgan, Henry Walters, and Joseph Widener.
Germain left the gallery in 1914 to fight for the French army in World War I and returned to rejoin the family company as a partner in 1920.
[1] In the early years Jacques Seligmann & Co. focused on the purchase and sales of decorative art related to Byzantine and Renaissance periods to satisfy the trends of the time.
World War I caused a lapse in sales in Europe, but interest in the United States was high specifically in modern art and Impressionism.
After the war sales resumed in Europe and Germain started to sell works by Pierre Bonnard, Honoré Daumier, Pablo Picasso, Vincent van Gogh, and other modern masters.
Other members of the family disapproved of Germain's modern interests, and he eventually formed a subsidiary, International Contemporary Art Company, Inc., along with business partner César Mange de Hauke.
His exhibitions frequently showed work by Paul Cézanne, Eugène Delacroix, Pierre-Auguste Renoir, Jean Ingres and Georges Seurat.
In Paris, the city offered to purchase Palais de Sagan in connection with plans for the Exposition Internationale des Arts et Techniques dans la Vie Moderne in 1937.
[1] In June 1940 as the Germans occupied Paris the company's sales plummeted and that summer the Seligmann galleries and family holdings were seized by the Vichy government, including Germain's private art collection.