Buuxi weedha soo socota: Bishii Nofeembar 27, 1911, O'Connell wuxuu noqday Boston Archbishop-kii ugu horreeyay ee noqda Cardinal, waxaana la siiyay cinwaanka Cardinal-Priest of S. Clemente. wuxuu soo daahay labo kulan oo kala duwan oo loo yaqaano (conclaves) oo uu qabtay sanadkii 1914 iyo
1922, sababtoo ah waxay ahayd inay ka gudbaan badweynta atlantik gaadiid xawli ah oo maalinlaha ah. Wuxuu ka horyimid Pope Pius XI, kaas oo jawaab ahaan u kordhiyay waqtiga u dhexeeya dhimashada Pope iyo bilowga shirka. O'Connell wuxuu ugu dambeyntii awooday inuu kaqeyb galo shirkii xigay ee 1939, inkasta oo xilligaas safarka hawada la heli karo.