“The most obvious constitutional result of the Civil War was the adoption of three landmark constitutional amendments. The 13th ended slavery forever in the United States, while the 14th made all persons born in the United States (including the former slaves) citizens of the nation and prohibited the states from denying anyone the privileges and immunities of American citizenship, due process or law, or equal protection of the law. Finally, the 15th Amendment, ratified in 1870, prohibited the states from denying the franchise to anyone based on “race, color, or previous condition of servitude.
These amendments, however, have their roots in the war itself, and in some ways can been seen as formal acknowledgments of the way the war altered the Constitution. Other changes came about without any amendments. Thus, the war altered the Constitution in a variety of ways. A review of some of them underscores how the Union that President Lincoln preserved was fundamentally different — and better — than the Union he inherited when he became president.” Read more here.