He taught for 25 years at Catholic University in Washington, D.C., and then served in the diplomatic service of the Holy See as an Apostolic Nuncio and archbishop.
He played a key role in arranging for bishops from the Communist-led countries of Eastern Europe to attend the Second Vatican Council.
[1] On 21 May 1949, Pope Pius XII named him titular archbishop of Rhizaeum and Apostolic Nuncio to both Haiti and the Dominican Republic.
[2] He received his episcopal consecration on 30 June 1949 from Archbishop Amleto Cicognani, Apostolic Nuncio to the United States, at the Shrine if the Immaculate Conception in Washington, D.C.[1] On 21 November 1953, Pope Pius appointed him Apostolic Nuncio to Peru.
[5] Pope John used him as an intermediary, first with the Russian Embassy in Ankara and then with the representatives of the other Eastern European countries there, to win the approval of those governments to allow their Catholic bishops to attend the Second Vatican Council.