Before Lincoln took office on March 4, 1861, a provisional Confederate government was established on February 8, 1861. It was considered illegal by the United States federal government, and many Northerners thought of the Confederates as traitors. After war began in April, four slave states of the Upper South—Virginia, Arkansas, Tennessee, and North Carolina—also joined the Confederacy. The Confederacy later accepted the slave states of Missouri and Kentucky as members, accepting rump state assembly declarations of secession as authorization for full delegations of representatives and senators in the Confederate Congress; they were never substantially controlled by Confederate forces, despite the efforts of Confederate shadow governments, which were eventually expelled. The government of the United States (the Union) rejected the claims of secession as illegitimate.