The New School's enthusiasm for moral reform and voluntary societies was evident in its increasing identification with the abolitionist movement. The Old School, however, was convinced that the General Assembly and the larger church should not legislate on moral issues that were not explicitly addressed in the Bible. This effectively drove the majority of Southern Presbyterians to support the Old School faction. The first definitive split over slavery occurred within the New School Presbyterian Church. In 1858, Southern synods and presbyteries belonging to the New School withdrew and established the pro-slavery United Synod of the Presbyterian Church. Old School Presbyterians followed in 1861 after the start of hostilities in the American Civil War. In May, the Old School General Assembly passed the controversial Gardiner Spring Resolutions, which called for Presbyterians to support the Constitution and Federal Government of the United States. In response, representatives of Old School presbyteries in the South met in December at Augusta, Georgia, to form the Presbyterian Church in the Confederate States of America. The Presbyterian Church in the CSA absorbed the smaller United Synod in 1864. After the Confederacy's defeat in 1865, it was renamed the Presbyterian Church in the United States (PCUS) and was commonly nicknamed the "Southern Presbyterian Church" throughout its history, while the PCUSA was known as the "Northern Presbyterian Church". Old School-New School reunion in the North By the 1850s, New School Presbyterians in the North had moved to more moderate positions and reasserted a stronger Presbyterian identity. This was helped in 1852 when the Plan of Union between the New School Church and the Congregationalists was discontinued. Northern Presbyterians of both the Old and New School participated in the Christian Commission that provided religious and social services to Union soldiers during the Civil War. Furthermore, both schools boldly proclaimed the righteousness of the Union cause and engaged in speculation about the role of a newly restored America in ushering in the millennium. This was, in effect, the Old School's repudiation of its teaching against involving the church in political affairs. A majority of Old School leaders in the North were convinced of the orthodoxy of the New School. Some within the Old School, chiefly Princeton theologian Charles Hodge, claimed that there were still ministers within the New School who adhered to New Haven theology. Nevertheless, the Old and New School General Assemblies in the North and a majority of their