[3] Holding the rank of captain, Hallinan was wounded in action on Biak Island near Papua and received the Purple Heart in 1944.
[4] In 1963, Hallinan earned a doctorate in history from Western Reserve University; his dissertation was on Richard Gilmour, the bishop of Cleveland from 1872 to 1891.
[3] In an attempt to increase the role of the laity in the church, Hallinan appointed more than 125 lay men and women to ecclesiastical positions.
[3] In his final years, he was assisted in the governance of the archdiocese by his protégé and auxiliary bishop, Joseph Bernardin, who would later become a cardinal and Archbishop of Chicago.
Recognized as one of the "foremost advocates of social and religious liberalism" in the American South,[9] Hallinan became known for his personal dedication to the civil rights movement and the cause of racial equality.
We decided to move at this time to desegregate archdiocesan schools, first, because it's right, and second, because an excellent climate of opinion and action already exists here.
"[2] In 1964, Hallian was one of four Atlanta civic leaders who sponsored a banquet honoring Dr. Martin Luther King Jr., after he received the Nobel Peace Prize.
He praised King as a "pioneer in a new dynamic of peace, expressed in the formula, 'I will walk in liberty, O Lord, because I seek thy precepts' (Psalms 119:45).
"[3] Hallinan also sent priests and nuns to participate in the 1965 Selma to Montgomery marches In Alabama, and encouraged Atlanta Catholics to open their neighborhoods "so Negroes can exercise the right of every American to live where he wishes.
Hallinan was also an advocate of ecumenism, and once wrote, "Never has this longing for Christian unity been more evident...We are growing more conscious that the Holy Spirit of God, brooding over our distressed world and our divided Christendom, is stirring now the souls of men in many places, providing the light and strength without which reunion remains an empty dream.
"[2] Hallinan He befriended such progressive minds as the theologian Reverend Hans Küng and Cardinal Leo Joseph Suenens.
[3] Hallinan supported the cautious approach of Pope Paul VI towards internal renewal in the church, saying, "We need some kind of brake for safety's sake.
At a study conference of the Clergy and Laymen Concerned about Vietnam (CALCAV), he declared, "Our conscience and our voice must be raised against the savagery and terror of war.