Maurice Samuel’s fifty-year career as a Zionist began in an era of formidable opposition and concluded in one when support for Israel had become a dogma. Samuel’s Zionist mentors included: Chaim Weizmann, Samuel’s chemistry teacher at Manchester University; Nachman Syrkin, briefly Samuel’s father-in law; the orator Shmaryahu Levin and the poet Chaim Nachman Bialik. Samuel, an itinerant public-speaker and author, held his only steady job as a functionary for the Zionist Organization of America (ZOA) in the 1920s. He wrote frequently for ZOA’s journal The New Palestine. Under the editorial eye of Meyer Weisgal, Samuel made a name as a sharp-tongued, sharp-penned promoter of Zionism. Samuel presented the cause in articles, films, and five books, including: What Happened in Palestine (1929), On the Rim of the Wilderness (1931), Harvest in the Desert (1944), Level Sunlight (1953) and Light on Israel (1968). The first and last in this series were written in the aftermath of epoch-making events, the outbreak of Palestinian Arab violence in 1929 and The Six Day War of 1967. In What Happened in Palestine Samuel offered eye-witness testimony to the failures of the British authorities and the complexity of Arab reactions. Samuel’s advocacy, as in the propaganda film "Rebirth" (1935), did not shy away from Arab-Israeli conflict, which he viewed as remediable by continued proof of positive Zionist achievements, above all those of the chalutzim (pioneers). Harvest in the Desert ranks as one of the best pre-state accounts if Israel. It signaled a change in Jewish Publication Society policy – hitherto neutral on Zionism. Level Sunlight, which supported controlled immigration, earned him the wrath of PM David Ben Gurion. Light on Israel showed Samuel increasingly detached from the realities of the new state. This paper traces the peculiar passage of a Zionist enthusiast turned ex-expert.