Which Bishop(s) in the USA allowed American Servicemen to assist Episcopalian priests as altar boys and to receive the sacraments in the Episcopal Church during WW I and even possibly during WW II? Wasn't this ecumenism in its earliest form?
During World War I, it is true that we did not yet have True Orthodox Churches as the ROCOR did not separate from the MP until after 1917, and the Old-Calendarists in Greece did not form a Synod until 1935.