Which slavery related event occurred first

The Kansas-Nebraska Act allowed each territory to decide the issue of slavery on the basis of popular sovereignty. Kansas with slavery would violate the Missouri Compromise, which had kept the Union from falling apart for the last thirty-four years.

Explanation:

abraham lincoln was the president of usa and he had asked the audience to make a pledge on equality.

his pledge was:

“it is my earnest desire to know the will of the providence.”

lincoln also had hatred for people who condoned and practiced slavery and so he pledged:

""and if i can learnt what it is i can do it"" this is another pledge by abraham to reassure the congregation on how to deal with the providence will.

explanation:

hope this !