Johnston surrendered April 26, Richard Taylor surrendered May 4th, Kirby Smith surrendered May 26. What's your point?
"but your precious Confederacy held on to it long after Lincoln was dead and gone".
The Confederacy died at Appomattox Courthouse (and the principles of the American Revoloution along with it). You can say it lasted another month because some units hadn't formally surrendered yet if you want. But that hardly supports your remark.