Why did Lincoln choose to limit his proclamation mostly to rebellious states?

My answer: Lincoln chose this because he did not want to anger the border states that remained in the Union?

Is this correct?

Right.

That is partially correct. Lincoln's decision to limit the scope of the Emancipation Proclamation to rebellious states was primarily a strategic move.

First and foremost, Lincoln wanted to present the proclamation as a military action rather than a political one. By focusing on rebellious states that were actively engaged in the Civil War, Lincoln framed the proclamation as a military necessity to weaken the Confederate war effort and undermine its labor force. This helped to legitimize the proclamation within the context of the ongoing war.

Additionally, Lincoln was mindful of the delicate political situation in the border states, which were slaveholding states that remained loyal to the Union. These states, such as Kentucky, Maryland, Missouri, and Delaware, were crucial to maintaining the Union's geographical integrity. Lincoln wanted to avoid pushing them into secession or strengthening the Confederate cause within those states. By excluding the border states from the Emancipation Proclamation, Lincoln aimed to prevent triggering an adverse reaction that could potentially jeopardize the Union's control over those territories.

In essence, Lincoln's decision to limit the proclamation mostly to rebellious states was driven by the dual objectives of bolstering the Union war effort and maintaining political stability within the border states.