How did Lincoln's reasons for fighting change over time?

Initially, Lincoln's primary reason for fighting in the Civil War was to preserve the Union and maintain national unity. However, as the war progressed, he increasingly recognized the moral imperative to abolish slavery, viewing it as essential to achieving true national unity and justice. The issuance of the Emancipation Proclamation in 1863 marked a significant shift, framing the conflict as a struggle for freedom and human rights, rather than merely a political endeavor. Ultimately, Lincoln's evolving perspective reflected a deeper understanding of the war's implications for American society and its values.