Hitler to Defend His "Purging" In Address German Chancellor Faces Task of Converting Skeptics At Home and Placating World Abroad, Berlin, July 13 (A.P.) -Chancellor Hitler drew up a defense today of his purge-by death of the nazi ranks--a defense he presents to the world tonight in one of his greatest oratorical. challenges. While the "iron chancellor" sat down in seclusion to write his speech, his cohorts built up a super-stage for him before the all -nazi Reichstag. "We fight and pray for Hitler" was emblazoned on huge banners unfurled over the doors of the theatre where the Reichstag will hear the chancellor at 8 p. m. (about 2 p. m., eastern standard time). Not since his powers of oratory elevated him to the chancellorship some 18 months ago o and brought millions under the Swastika have Hitler and naziiem faced such a test. A two fold task confronted Hitlerto convert an untold number of skepties at home and to placate a world abroad, embittered by nazi Germany's financial and economic policies and mistrustful of its military aims. What the chancellor would say, bevond a defense of the bloody June 30 none knew. Some believed that he would come forward bluntly with an offer of international cooperation, designed to break the stranglehold of isolation that has been the fruit of the nazi foreign policy. What was regarded as an admission that "Der Fuehrer" faces a critical public tonight came from his own newspaper, the Volkische Beobachter, which exhorted Germany to "discipline." The newspaper complained: "It astonishing with what a lack of understanding a certain part of our public misses the true significance of the happenings in our time."