Lincoln believed that the federal government did not have the authority to abolish slavery; that would violate states' rights. But he was also Commander of the Armed Forces. An action against states which were in rebellion, a step towards their defeat, was entirely appropriate. The South interpreted it as a hostile act. This allowed Lincoln to abolish slavery to a limited extent, without igniting resistance from anti-abolitionist forces in the Union. None of the slaves who lived outside the border areas were immediately affected, and it was the invading Northern armies which enforced the prohibition.