Cardinal Francis George of Chicago.

Chicago, Ill. (CNA/EWTN News) - Cardinal Francis George, the Emeritus Archbishop of Chicago, passed away Friday morning after a long batter with cancer.

Archbishop Blase Cupich, who currently heads the archdiocese, remembered Cardinal George as "a man of peace, tenacity and courage."

At an April 17 press conference, Archbishop Cupich lauded the cardinal for his bravery in overcoming challenges, which included a battle with polio as a teenager that left his legs permanently weak.

"Cardinal George was a respected leader among the bishops of the United States," Archbishop Cupich noted, particularly pointing to his work to fight the clerical sex abuse scandal: "He stood strong among his fellow bishops and insisted that zero tolerance was the only course consistent with our beliefs."

The 78-year-old cardinal had been fighting cancer for several years. He was first diagnosed with bladder cancer in 2006 and underwent a five-hour surgery to remove his bladder and other parts of his body affected by cancer. In 2012, his doctors discovered that the cancer had returned, this time to his kidney and liver.

In an effort to battle the returning cancer, Cardinal George took part in a cancer drug clinical trial last year, which experimented with helping the body recognize cancerous cells through the immune system. After it was determined that his trial was proving to be ineffective, he halted the treatment in January.

The first Chicago native to become the city's archbishop, Cardinal George retired in 2014 amid his battle with cancer and was succeeded by Archbishop Cupich. He had shepherded the archdiocese since 1997.

Last year, he said that the cancer would likely be the cause of his death, but that he was counting on prayers so that he "might be of service to the Lord and His Church in the time left."

Cardinal George leaves behind a robust legacy as a leader among the American bishops and an influential figure in the global Church.

He worked with the U.S. bishops and Vatican to fight clerical sex abuse, prominently speaking in favor of a "zero tolerance" policy.

He was also a religious freedom advocate, strongly opposing regulations under the Obama administration that would require Catholic organizations to cooperate with providing abortion and contraception.

A long-time commenter on the state of culture, Cardinal George is known for once saying that he believed he would die in bed, his successor would die in prison, and his successor will die a martyr in the public square, but that the following successor would pick up the fragments of society and help to rebuild civilization.

Born Jan. 16, 1937, Francis Eugene George joined the Missionary Oblates of Mary Immaculate and was ordained a priest in 1963. He obtained a master's degree in philosophy at The Catholic University of America and a doctorate in American philosophy at Tulane University in New Orleans. He later studied at the Pontifical Urban University in Rome, where he earned Doctorate of Sacred Theology.

Pope John Paul II appointed him Bishop of Yakima in 1990. He became Archbishop of Portland, Oregon in 1997 and was appointed the following year to be the Archbishop of Chicago.

Elevated to the College of Cardinals in 1998, Cardinal George was appointed to numerous Vatican councils and congregations, including the Congregation for Divine Worship and the Discipline of the Sacraments, the Pontifical Council for Culture, the Congregation for Institutes of Consecrated Life and for Societies of Apostolic Life, and the Pontifical Council "Cor Unum."

Cardinal George was a papal appointee to the Synod of Bishops on Consecrated Life in 1994 and served as a delegate to the synod of bishops on several other occasions.

The cardinal served as president of the U.S. Conference of Catholic Bishops from 2007-2010. He was a member and advisor for numerous other committees at the U.S. bishops' conference, including those dealing with doctrine, missions, evangelization and catechesis, pro-life activities, divine worship, African American Catholics and religious liberty.

He was a board member for numerous organizations, including The Catholic University of America, the National Catholic Bioethics Center, the Basilica of the National Shrine of the Immaculate Conception and the National Catholic Office for Persons with Disabilities.

During his time as archbishop of Chicago, Cardinal George wrote pastoral letters on evangelization and the problem of racism. He also wrote two books reflecting on faith in relation to culture and the common good.

Archbishop Cupich recalled Cardinal George as a man who was close to the diocese that he led, "always choosing the Church over his own comfort and the people over his own needs."

He praised the cardinal for his example throughout his life, including his final battle with cancer.

"Let us heed his example and be a little more brave, a little more steadfast and a lot more loving," the archbishop said.