Zionist leader, Hebrew writer and editor in Poland, he came to London in 1915 to participate in the diplomatic negotiations that resulted in the issuing of the Balfour Declaration. During World War I, Sokolow traveled to Italy and the Vatican, and then to France, and secured the approval of the British, Italian, and French powers for the declaration before its publication. In 1919 he led the presentation of Zionist claims before the Peace Conference at Versailles. When the Jewish Agency for Palestine was created in 1929, Sokolow was elected its president. From 1931 to 1935 he was president of the World Zionist Organization. Sokolov was a man of vast learning, a prolific writer, and one of the great orators of the early Zionist movement.