It's hilarious to me when modern Republicans try to claim that Lincoln was a conservative when he was decried as a radical progressive by his detractors.
Hell Lincoln even called out conservative bullshit back then, saying that the policy of admitting new slaver States is contrary to the will of the founders and the traditions of the young nation.
From his speech at Cooper Union prior to his presidency:
But you say you are conservative - eminently conservative - while we are revolutionary, destructive, or something of the sort. What is conservatism? Is it not adherence to the old and tried, against the new and untried? We stick to, contend for, the identical old policy on the point in controversy which was adopted by "our fathers who framed the Government under which we live;" while you with one accord reject, and scout, and spit upon that old policy, and insist upon substituting something new. True, you disagree among yourselves as to what that substitute shall be. You are divided on new propositions and plans, but you are unanimous in rejecting and denouncing the old policy of the fathers. Some of you are for reviving the foreign slave trade; some for a Congressional Slave-Code for the Territories; some for Congress forbidding the Territories to prohibit Slavery within their limits; some for maintaining Slavery in the Territories through the judiciary; some for the "gur-reat pur-rinciple" that "if one man would enslave another, no third man should object," fantastically called "Popular Sovereignty;" but never a man among you is in favor of federal prohibition of slavery in federal territories, according to the practice of "our fathers who framed the Government under which we live." Not one of all your various plans can show a precedent or an advocate in the century within which our Government originated. Consider, then, whether your claim of conservatism for yourselves, and your charge or destructiveness against us, are based on the most clear and stable foundations.