How did the colonialism of Manifest Destiny further the expansion of slavery and sectional division (slave states vs. free states) that led to the Civil War?

The philosophy drove 19th-century U.S. territorial expansion and was used to justify the forced removal of Native Americans and other groups from their homes. The rapid expansion of the United States intensified the issue of slavery as new states were added to the Union, leading to the outbreak of the Civil War.

they wanted the u.s. to fight on the side of the central powers.

probally   a few days after there called