He then became a pivotal figure in the Brit Halutzim Dattiyim (“the League of Religious Pioneers”). During the early years of the Nazi era his work with the organisation, based in Berlin, allowed him some freedom to travel, both nationally and internationally, as it prepared adherents for emigration from the Reich to Mandatory Palestine. During this period, Handler became friendly with such pioneers as Chaim Arlosoroff (“the lost leader” of Zionism who was assassinated in 1934) and Chaim Weizmann, later the first President of Israel. As a walking compendium of Zionist history, Handler was the last person alive to have known such “founding fathers” well.