The successful 1863 Union siege of Vicksburg split the Confederacy in two at the Mississippi River, while Confederate general Robert E. Lee's incursion north failed at the Battle of Gettysburg.

[23] Background factors in the run up to the Civil War were partisan politics, abolitionism, nullification versus secession, Southern and Northern nationalism, expansionism, economics, and modernization in the antebellum period.

[42] He did not intend to invade Southern states, nor to end slavery where it existed, but he said he would use force to maintain possession of federal property,[42] including forts, arsenals, mints, and customhouses that had been seized.

Historian McPherson describes this win-win approach as "the first sign of the mastery that would mark Lincoln's presidency"; the Union would win if it could resupply and hold the fort, and the South would be the aggressor if it opened fire on an unarmed ship supplying starving men.

[74] A Unionist secession attempt occurred in East Tennessee, but was suppressed by the Confederacy, which arrested over 3,000 men suspected of loyalty to the Union; they were held without trial.

Some European observers at the time dismissed them as amateur and unprofessional,[88] but historian John Keegan concluded that each outmatched the French, Prussian, and Russian armies, and without the Atlantic, could have threatened any of them with defeat.

[115] The Southern economy nearly collapsed during the war due to multiple factors, the most notable being severe food shortages, failing railroads, loss of control over key rivers, foraging by Northern armies, and the seizure of animals and crops by Confederate forces.

When Virginia declared its secession in April 1861, Robert E. Lee chose to follow his home state, despite his desire for the country to remain intact and an offer of a senior Union command.

[143] McClellan resisted General-in-Chief Halleck's orders to send reinforcements to John Pope's Union Army of Virginia, which made it easier for Lee's Confederates to defeat twice the number of combined enemy troops.

At the same time, the Confederate stronghold of Vicksburg surrendered, giving the Union control of the Mississippi River, permanently isolating the western Confederacy, and producing the new leader Lincoln needed, Ulysses S.

Grant marched to the relief of Rosecrans and defeated Bragg at the Third Battle of Chattanooga,[171] eventually causing Longstreet to abandon his Knoxville Campaign and driving Confederate forces out of Tennessee and opening a route to Atlanta and the heart of the Confederacy.

Although he lacked resources to beat Union armies, he built up a formidable arsenal at Tyler, along with his own Kirby Smithdom economy, a virtual "independent fiefdom" in Texas, including railroad construction and international smuggling.

While Lee was preparing for an attack on Richmond, Grant unexpectedly turned south to cross the James River and began the protracted Siege of Petersburg, where the two armies engaged in trench warfare for over nine months.

After relieving Sigel, and following mixed performances by his successor, Grant finally found a commander, General Philip Sheridan, aggressive enough to prevail against the army of Maj. Gen. Jubal A.

[202][203] In an untraditional gesture and as a sign of Grant's respect and anticipation of peacefully restoring Confederate states to the Union, Lee was permitted to keep his sword and horse, Traveller.

[i] On April 26, the same day Sergeant Boston Corbett killed Booth at a tobacco barn, Johnston surrendered nearly 90,000 troops of the Army of Tennessee to Sherman at Bennett Place, near present-day Durham, North Carolina.

[222] Finally, on October 18, Russell advised the Admiralty that the time specified in his June message had elapsed and "all measures of a restrictive nature on vessels of war of the United States in British ports, harbors, and waters, are now to be considered as at an end".

The Republicans' counterargument that slavery was the mainstay of the enemy steadily gained support, with the Democrats losing decisively in the 1863 elections in the Northern state of Ohio, when they tried to resurrect anti-black sentiment.

[266] The Emancipation Proclamation legally freed the slaves in states "in rebellion," but, as a practical matter, slavery for the 3.5 million black people in the South effectively ended in each area when Union armies arrived.

About 190,000 volunteered, further enhancing the numerical advantage the Union armies enjoyed over the Confederates, who did not dare emulate the equivalent manpower source for fear of undermining the legitimacy of slavery.

Lincoln's fears of making slavery a war issue were based on a harsh reality: abolition did not enjoy wide support in the west, the territories, and the border states.

[289] It comprised multiple complex methods to resolve the outstanding issues of the aftermath, the most important of which were the three "Reconstruction Amendments" to the Constitution: the 13th outlawing slavery (1865), the 14th guaranteeing citizenship to former slaves (1868), and the 15th prohibiting the denial of voting rights "on account of race, color, or previous condition of servitude" (1870).

[290] President Johnson, who took office in April 1865, took a lenient approach and saw the achievement of the main war goals as realized in 1865, when each ex-rebel state repudiated secession and ratified the Thirteenth Amendment.

Many veterans on both sides were elected to political office, including five U.S. Presidents: Ulysses Grant, Rutherford B. Hayes, James A. Garfield, Benjamin Harrison, and William McKinley.

[294] The last theme includes moral evaluations of racism and slavery, heroism in combat and behind the lines, and issues of democracy and minority rights, as well as the notion of an "Empire of Liberty" influencing the world.

Military history has largely developed outside academia, leading to a proliferation of studies by non-scholars who nevertheless are familiar with the primary sources and pay close attention to battles and campaigns and who write for the general public.

Some claims revolve around the insignificance of slavery as a cause; some appeals highlight cultural differences between North and South; the military conflict by Confederate actors is idealized; in any case, secession was said to be lawful.

The organization quickly grew in influence during the late 19th and early 20th centuries and ended up playing a pivotal role in shaping the collective memory of the American Civil War.

Through speeches, publications, and curriculum influence, the UDC worked to recast the Confederacy in a sympathetic light, framing the Civil War as a struggle against Northern aggression.

In recent years, the role of the UDC and the Lost Cause myth has come under scrutiny amid debates over Confederate monuments and systemic racism in the United States.