[2][3][4] In WWI he was "wounded three times and cited for bravery while serving in the French artillery and air force.
He was a flight captain and attaché of French Embassy in Washington,[4][5][6] and president of Patou (perfume) from July 1940[7][8] before quitting,[4] giving his time to help de Gaulle.
De Sieyes was a founding member[8][9][10][11][12] of France Forever on 29 June 1940.
In September 1940, the Fighting French Committee of the Emergency Aid of Pennsylvania, was established "by Mrs. Eugene Houdry, Mrs. Pierre Quilleret, Mr. Jacques de Sieyès, then delegate of General de Gaulle and Dr. Albert Simard to support and encourage the thousands of young Frenchmen and women serving in England with the British forces.
[14] In London, he announced: "The French people are not only starving, but absolutely ready for revolt — if they had the means to carry it out.