During the First World War Szwarc returned to Poland. In 1919 he met and married his wife, Guina, a writer, and together they returned to Paris after the war. Until the Second World War, Szwarc lived in Paris and his paintings and sculptures were bought by collectors in Germany, Poland, the United States, and by several museums. It was during this period between the wars that he produced some of his most outstanding and original work in hammered copper, exhibited in the Salon des Tuileries and the subject of a monograph by the celebrated art critic Louis Vauxcelles. Vauxcelles writes of Szwarc: