What steps did Lincoln take to preserve the union before and after the fighting at fort Sumter?

Before and after the brief engagement centered upon Fort Sumter, Lincoln's steps to preserve the Union were quite carefully taken. For one thing, he sought to do nothing that would upset the neutrality of the border states of Missouri, Kentucky, Maryland, and Delaware. For another thing, he attempted to force a decision upon the Southern states that had seceded, placing them in a position to be guilty of causing the war which he repeatedly declared he did not want.