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Ransom, Roger L. The Confederate States of America: What Might Have Been. W.W. Norton 2005.

Ransom, Roger L. The Confederate States of America: What Might Have Been
Divergence: 1862 CE
What if: Shiloh was a Confederate victory, thus slowing Union progress in the west. That victory, plus rebel successes at Chattanooga and Gettysburg, led to a stalemate in 1864 that was terminated with the election of Horatio Seymour to the U.S. presidency and then the Treaty of Toronto.
Summary: Mixes an allohistorical scenario for Southern victory with an analysis of the South's motives for secession, how it might have won the Civil War, its prospects for economic survival (including emancipation) over the next decades, and how its existence would affect the rest of the world. An epilog suggests a re-union of the states after the bloody world war of 1915 found the Union and Confederacy on opposite sides.
Published: W.W. Norton 2005 (0393059677BUY), 2006 (0393329119BUY).

Ransom, Roger L. "Fact and Counterfact: The "Second American Revolution" Revisited"
Summary: Addresses in shorter form many of the topics subsequently considered in his longer The Confederate States of America: What Might Have Been, but is not explicit in considering a particular timeline.
Published: In Civil War History March 1999 (vol. 45, no. 1).