In 1861, the Democratic party had wide support across the South. Even today, some people believe erroneously that the Democratic party alone supported slavery. But, certainly, the Democrats largely supported the extension of slavery. Yet, The Democrats also generally embraced the Irish and German immigrants in the decades leading up to the Civil War. In the decades of the ante-bellum era, the German and especially the Irish immigrants were seen as repugnant by many native Anglo Americans. A young Congressman, Jefferson Davis, was friends with prominent Irish immigrants in Vicksburg, Mississippi. His plantation was near Vicksburg.
The future president of the Confederate States of America earned a measure of fame among immigrants everywhere when he attacked the nativist members of Congress and their attempt to restrict immigration. As a freshman Representative in 1844-1845, he castigated the nativist members for their “sordid character [and] their arrogant assumption.” He argued that instead of restricting immigration, Congress should make becoming a citizen easier. It was one of the ironies of American history that a well-known supporter of immigrants was also a large slave owner. No one said ante-bellum politics were simple.
David T. Gleeson, The Irish in the South (Univ. of North Carolina Press 2001), p. 102.