Why did the North want to preserve the Union?

assuming that you are talking about the one in egypt: hecka oil

explanation:

to act quickly in times of danger to the united states

because you have to act quickly if you want to live/survive.

the emancipation proclamation was the aim of the war change to include the freeing of slaves in addition to preserving the union. the 13th amendment, which abolished slavery in the u.s. was passed on december 6th 1865.

as promised, lincoln waited to unveil the proclamation until he could do so with success from the union military advance. on september 22nd 1862, after a victory at antietam, he publicly announced a preliminary emancipation proclamation, declaring all slaves free in the rebellious states as of january 1st 1863.

"this speech"? what speech are you talking about?