[DarkSavant]

Many States seceded over slavery

The Union declared war to "preserve the Union"

The Union allowed their slave states to keep slaves during the war.

[DoodleDawg]

The Union declared war to "preserve the Union"

There was no declaration of war. The South launched the war when they attacked Sumter.

[IrishBrigade]

The Union allowed their slave states to keep slaves during the war.

the Federal government maintained the same stance with ‘their slave states’ as it had with the antebellum states that subsequently seceded; can’t imagine what point you’re attempting to make...