Certainly the North defeated the South in the military engagement. Yes, the slaves were freed (though I would quibble about how much and when). Liberals however, did not defeat the reasoning behind slavery, which is White Supremacy and Conservatism. White Supremacy is what fueled the South in their ability and desire to maintain and expand slavery, and contrary to popular belief, people in the North were not keen on fighting and dying for the dignity of Black people.
Conservatism is in my opinion, a useless ideology. It is based on the concepts of hierarchy (ordained by god), that was born of defending Monarchy. While Monarchy is for the most part, a diminished form of government, the attitude that "natural betters", usually wealthy White Men, should be in charge and able to do things with impunity, still remains.
The fact that we still have such a strong conservative movement (still based on racial and religious bigotry). The fact that more than half our states are completely controlled by Conservative Government. The fact that our Federal Government consists of a Liberal party that represents more than 60% of the population and yet the government is split nearly 50/50 in power with the Supreme Court solidly in Conservative hands for the next few decades.
History has shown that when conservatism shifts over to fascism, which is its natural end point, that it ends in disaster for the fascists, so yes eventually we will win, but look at what it did to Germany. Look at what happened in England, France, Spain, etc... as they transitioned from arch conservative or fascist modes of government to more liberal ideals.