Originally Lincoln said that slavery couldn't be abolished because of the Constitution. Slaves were property and slave owners had the right to their property. Later this only applied to loyalists. Still later, Lincoln proposed the 13th amendment, abolishing slavery (even though he still favored compensation for slave owners). Why this shift in Lincoln's thinking and how did Lincoln justify taking away property from loyal slave owners which he previously said this was unconstitutional?

Please cite sources if you have them. Thanks!