American Cardinal; former archbishop of Baltimore (one of the shortest administrations in its history). Military Vicar of the Armed Forces. Pro-Grand Master of the Equestrian Order of the Holy Sepulchre of Jerusalem.
 
TLS – Typewritten Letter Signed, one page 20 March 2012, on his official letterhead as Grand Master of the Equestrian Order. Reads:  Thank you for your kind words of congratulations on my elevation to the College of Cardinals.  This honor is a reflection of the importance of the work we must do together to support the holy work of the Church in the land of our Lord. I am grateful to our Holy Father for his confidence in me and pledge my continued support and fraternal love as I continue to serve the Church in the Holy Land. As well, I am grateful to the many people who throughout my many years of service to the Church have taught me the meaning of selfless service to Jesus, his Church and to all God’s people. Once again, thank you for your kind words and please join me in praying for our Holy Father and for all who carry out the work of Jesus on behalf of the Church we serve…
 
O’Brien has been the Grand Master of the Equestrian Order of the Holy Sepulchre of Jerusalem since March 2012, having previously served as Pro-Grand Master since August 29, 2011. He previously held positions as 15th Archbishop of Baltimore from 2007 to 2011, and as seventh Archbishop for the Military Services from 1997 to 2007.