Lincoln sought to preserve Slavery through a Constitutional Amendment

"Lincoln instructed Seward to make sure that the amendment said that "the Constitution should never be altered so as to authorize Congress to abolish or interfere with slavery in the states" where it existed. In addition, writes Goodwin, Lincoln instructed Seward, who would become his Secretary of State, to get a federal law introduced that would have made various personal liberty laws that existed in some Northern states illegal. These state laws were meant to nullify the federal Fugitive Slave Act, an act that Lincoln very strongly supported. Far from putting slavery "on the path to extinction," these actions of Lincoln’s would have granted it more powerful government support than ever." 

Read Tom DiLorenzo taking apart a Lincoln cultist professor's article published in the New York Times, at LewRockwell.com