What two reasons does Lincoln glve for launching military action against the South?

1, I need points to get answers for my questions but they were building up their military after the treaty of Versailles

To honor the common soldiers and sailors who have not abandoned their posts. to teach Americans that change can only come peacefully, through elections, not through war. to guarantee that every state continues to have a republican form of government, as promised by the Constitution.

More than 4 million enslaved hunan beings in the south and they touched every aspect of the regions social, political and economic life.