Which one is this? Not the historical XIIIth, surely -- do you mean the Crittenden Compromise?
No. The Crittedon Compromise was over expansion of slavery to the West which Lincoln refused to compromise on. The amendment of 1861 would have guranteed to protect slavery in the 15 states where it then existed by making it 'unconstitutional' to end slavery. Lincoln said he would support it. It was silent on Westward expansion. The amendment was a despiration move by 'moderates' in congress to bring the southern states back and avoid war. The southern states all rejected it saying that slavery was already protected and that expansion was what really mattered to them. The reality is that slavery itself was not the cause of the war. Expansion of slavery was the cause. Lincoln and the South both understood the same economics. Without expansion, the slave economy would have imploded on itself as the slave population doubled every generation. Lincoln saw 'containment' as the way to end slavery, while the south saw expansion as absolutluy necessary to keep their institutions alive.