Mr. Frank Duff is known universally in connection with the Legion of Mary, the greatest movement of the lay apostolate to grow in God's Church in the twentieth century. The Communists have tried to subjugate it and, in doing so, to crush the Church out of existence among its peoples. They have failed. This mighty godless force, which has met with success after success in the long established Catholic countries of Europes, has failed to liquidate the infant Church in China. The main reason for that failure is the Legion of Mary. This same spirit which has given Mary's Legion martyrs in China has enabled it to accomplish unbelievable feats of apostolate throughout the world. It is the spirit of the Legion that has made all this possible. That spirit is contained in the Handbook, which all active members possess. It is explained and applied in the various articles published quarterly in Maria Legionis, the Legion's official international journal.