Why was the election of 1860 so controversial?

The 1860 Republican National Convention, in Chicago, nominated Lincoln, a moderate former one-term Representative from Illinois, as its standard-bearer. Its platform promised not to interfere with slavery in the Southern states but opposed the further extension of slavery into the Western territories.The Republican Party was relatively new; 1860 was only the second time the party had a candidate in the presidential race. The Constitutional Union Party was also new; 1860 was the first and only time the party ran a candidate for president. The results of the 1860 election pushed the nation into war.

in the declaration of independence, thomas jefferson announced that every human being has “certain unalienable rights,” among which are those to “life, liberty, and the pursuit of " hope i