accomplishment was his mediation of the conflict between the Mexican government and the Catholic Church in Mexico which had escalated into a violent armed conflict, known as the Cristero rebellion. It was in the security interests of the United States not to have turmoil in its southern neighbor, not least because of the exodus of Mexicans to the U.S. in the conflict zones. Morrow's efforts of mediation were successful, He was aided in his efforts by Father John J. Burke of the National Catholic Welfare Conference. The Vatican was also actively suing for peace. After the 1928 assassination of the newly re-elected President Álvaro Obregón, former president Calles was ineligible to serve again due to term limits, and the Mexican Congress named Emilio Portes Gil as president. In practice, Calles remained in control of power in a period known as the Maximato. Portes Gil as interim president in December 1928, allowed Morrow and Burke to revitalize their peace initiative. Portes Gil told a foreign correspondent on May 1 that "the Catholic clergy, when they wish, may renew the exercise of their rites with only one obligation, that they respect the laws of the land." Morrow managed to bring the war parties to agreement on June 21, 1929. His office drafted a pact called the arreglos (agreement) that allowed worship to resume in Mexico and granted three concessions to the Catholics: only priests who were named by hierarchical superiors would be required to register, religious instruction in the churches (but not in the schools) would be permitted, and all citizens, including the clergy, would be allowed to make petitions to reform the laws. The anticlerical articles of the Constitution of 1917 remained in place, but were not systematically enforced. Later career In 1930 he was elected as a Republican to the United States Senate to fill the vacancy caused by the resignation of Walter Evans Edge. At the same time he was elected for the full term commencing March 4, 1931. He served in the Senate from December 3, 1930, until his death in Englewood, New Jersey, on October 5, 1931. Death Following a speaking engagement in New York City, Morrow suffered a stroke in his sleep at his home in Englewood, New Jersey and died the next afternoon on October 5, 1931. A partner at J.P. Morgan, Morrow was one of the richest men in New Jersey. Morrow's death occurred