June 1919

DeValera leaves Ireland for America, as part of a prolonged effort to persuade the international community to recognise Ireland as an independent state.

An indepth article by David McCullagh examining the political and personal  impact of De Valera's visit to America (including how he got his new title) can be read here.

An analysis of the various parties involved:

https://www.dail100.ie/en/long-reads/eamon-de-valera-in-america/