The Emancipation Proclamation and Thirteenth Amendment brought about by the Civil War were important milestones in the long process of ending legal slavery in the United States. Almost from the beginning of his administration, abolitionists and radical Republicans pressured Abraham Lincoln to issue an Emancipation Proclamation. Although Lincoln personally abhorred slavery, he felt confined by his constitutional authority as president to challenge slavery only in the context of necessary war measures. He also worried about the reactions of those in the loyal border states where slavery was still legal. Lincoln is said to have summed up the importance of keeping the border states in the Union by saying "I hope to have God on my side, but I must have Kentucky."