According to Lincoln, what was the main reason for fighting the Civil war?

To show the south his power as president.

To preserve the Union.

slavery

To show the strength of the United States to other nations.

The principle reason for fighting the civil war according to Lincoln was to preserve the Union. Lincolns policies before the war were to maintain slavery in place in the south. It was only during the war that slavery became a much larger issue. Lincolns advisers advised against the Emancipation proclimation later announced by Lincoln ending slavery in the South. Lincolns position before the war that slavery was a state decision.

To preserve the Union.

slavery

That is why he did it he did not believe people should be slaves