Just weeks after Lincoln followed Buchanan in the presidency, Southern states began seceding from the U.S., and the American Civil War started. Historians fault Buchanan for his failure to address the issue of slavery and the secession of the Southern states, and generally consider him to be one of the worst presidents in U.S. history. His parents were both of Ulster Scot descent, his father having emigrated from Milford, County Donegal, Ireland, in 1783. Shortly after Buchanan's birth the family moved to a farm near Mercersburg, Pennsylvania, and in 1794 the family moved to town. Buchanan's father became the wealthiest person in town, as a merchant, farmer, and real estate investor.