Civil War, in U.S. history, conflict (1861?65) between the Northern states (the Union) and the Southern states that seceded from the Union and formed the Confederacy. It is generally known in the South as the War between the States and is also called the War of the Rebellion (the official Union designation), the War of Secession, and the War for Southern Independence. The name Civil War, although much criticized as inexact, is most widely accepted.

Causes
The name Civil War is misleading because the war was not a class struggle, but a sectional combat having its roots in political, economic, social, and psychological elements so complex that historians still do not agree on its basic causes. It has been characterized, in the words of William H. Seward, as the ?irrepressible conflict.? In another judgment the Civil War was viewed as criminally stupid, an unnecessary bloodletting brought on by arrogant extremists and blundering politicians. Both views accept the fact that in 1861 there existed a situation that, rightly or wrongly, had come to be regarded as insoluble by peaceful means.

In the days of the American Revolution and of the adoption of the Constitution, differences between North and South were dwarfed by their common interest in establishing a new nation. But sectionalism steadily grew stronger. During the 19th cent. the South remained almost completely agricultural, with an economy and a social order largely founded on slavery and the plantation system. These mutually dependent institutions produced the staples, especially cotton, from which the South derived its wealth. The North had its own great agricultural resources, was always more advanced commercially, and was also expanding industrially.

Hostility between the two sections grew perceptibly after 1820, the year of the Missouri Compromise, which was intended as a permanent solution to the issue in which that hostility was most clearly expressed?the question of the extension or prohibition of slavery in the federal territories of the West. Difficulties over the tariff (which led John C. Calhoun and South Carolina to nullification and to an extreme states' rights stand) and troubles over internal improvements were also involved, but the territorial issue nearly always loomed largest. In the North moral indignation increased with the rise of the abolitionists in the 1830s. Since slavery was unadaptable to much of the territorial lands, which eventually would be admitted as free states, the South became more anxious about maintaining its position as an equal in the Union. Southerners thus strongly supported the annexation of Texas (certain to be a slave state) and the Mexican War and even agitated for the annexation of Cuba.

The Compromise of 1850 marked the end of the period that might be called the era of compromise. The deaths in 1852 of Henry Clay and Daniel Webster left no leader of national stature, but only sectional spokesmen, such as W. H. Seward, Charles Sumner, and Salmon P. Chase in the North and Jefferson Davis and Robert Toombs in the South. With the Kansas-Nebraska Act (1854) and the consequent struggle over ?bleeding? Kansas the factions first resorted to shooting. The South was ever alert to protect its ?peculiar institution,? even though many Southerners recognized slavery as an anachronism in a supposedly enlightened age. Passions aroused by arguments over the fugitive slave laws (which culminated in the Dred Scott Case) and over slavery in general were further excited by the activities of the Northern abolitionist John Brown and by the vigorous proslavery utterances of William L. Yancey, one of the leading Southern fire-eaters.

The Election of 1860
The ?wedges of separation? caused by slavery split large Protestant sects into Northern and Southern branches and dissolved the Whig party. Most Southern Whigs joined the Democratic party, one of the few remaining, if shaky, nationwide institutions. The new Republican party, heir to the Free-Soil party and to the Liberty party, was a strictly Northern phenomenon. The crucial point was reached in the presidential election of 1860, in which the Republican candidate, Abraham Lincoln, defeated three opponents?Stephen A. Douglas (Northern Democrat), John C. Breckinridge (Southern Democrat), and John Bell of the Constitutional Union party.

Lincoln's victory was the signal for the secession of South Carolina (Dec. 20, 1860), and that state was followed out of the Union by six other states?Mississippi, Florida, Alabama, Georgia, Louisiana, and Texas. Immediately the question of federal property in these states became important, especially the forts in the harbor of Charleston, S.C.. The outgoing President, James Buchanan, a Northern Democrat who was either truckling to the Southern, proslavery wing of his party or sincerely attempting to avert war, pursued a vacillating course. At any rate the question of the forts was still unsettled when Lincoln was inaugurated, and meanwhile there had been several futile efforts to reunite the sections, notably the Crittenden Compromise offered by Sen. J. J. Crittenden. Lincoln resolved to hold Sumter. The new Confederate government under President Jefferson Davis and South Carolina were equally determined to oust the Federals.

Sumter to Gettysburg
When, on Apr. 12, 1861, the Confederate commander P. G. T. Beauregard, acting on instructions, ordered the firing on Fort Sumter, hostilities officially began. Lincoln immediately called for troops to be used against the seven seceding states, which were soon joined by Arkansas, North Carolina, Virginia, and Tennessee, completing the 11-state Confederacy. In the first important military campaign of the war untrained Union troops under Irvin McDowell, advancing on Richmond, now the Confederate capital, were routed by equally inexperienced Confederate soldiers led by Beauregard and Joseph E. Johnston in the first battle of Bull Run (July 21, 1861). This fiasco led Lincoln to bring up George B. McClellan (1826?85), fresh from his successes in W Virginia (admitted as the new state of West Virginia in 1863).

After the retirement of Winfield Scott in Nov., 1861, McClellan was for a few months the chief Northern commander. The able organizer of the Army of the Potomac, he nevertheless failed in the Peninsular campaign (Apr.?July, 1862), in which Robert E. Lee succeeded the wounded Johnston as commander of the Confederate Army of Northern Virginia. Lee planned the diversion in the Shenandoah Valley, which, brilliantly executed by Thomas J. (Stonewall) Jackson, worked perfectly. Next to Lee himself Jackson, with his famous ?foot cavalry,? was the South's greatest general.

Lee then went on to save Richmond in the Seven Days battles (June 26?July 2) and was victorious in the second battle of Bull Run (Aug. 29?30), thoroughly trouncing John Pope. However, he also failed in his first invasion of enemy territory. In September, McClellan, whom Lincoln had restored to command of the defenses of Washington, checked Lee in Maryland. When McClellan failed to attack the Confederates as they retreated, Lincoln removed him again, this time permanently.

Two subsequent Union advances on Richmond, the first led by Ambrose E. Burnside and the second by Joseph Hooker, ended in resounding defeats (Dec. 13, 1862, and May 2?4, 1863). Although Lee lost Jackson at Chancellorsville, the victory prompted him to try another invasion of the North. With his lieutenants Richard S. Ewell, James Longstreet, A. P. Hill, and J. E. B. (Jeb) Stuart, he moved via the Shenandoah Valley into S Pennsylvania. There the Army of the Potomac, under still another new chief, George G. Meade, rallied to stop him again in the greatest battle (July 1?3, 1863) of the war.

Naval Engagements
With the vastly superior sea power built up by Secretary of the Navy Gideon Welles, the Union established a blockade of the Southern coast, which, though by no means completely effective, nevertheless limited the South's foreign trade to the uncertain prospects of blockade-running. In cooperation with the army the Union navy also attacked along the coasts. The forts guarding New Orleans, the largest Confederate port, fell (Apr. 28, 1862) to a fleet under David G. Farragut, and the city was occupied by troops commanded by Benjamin F. Butler (1818?93). The introduction of the ironclad warship had revolutionized naval warfare, to the ultimate advantage of the industrial North. On the other hand, Confederate cruisers, built or bought in England and captained by men such as Raphael Semmes, destroyed or chased from the seas much of the U.S. merchant marine.

The War in the West
That the ?war was won in the West? has become axiomatic. There the rivers, conveniently flowing either north (the Cumberland and the Tennessee) or south (the Mississippi), invited Union penetration, as they did not in Virginia. In Feb., 1862, the Union gunboats of Andrew H. Foote forced the Confederates to retire from their post Fort Henry on the Tennessee to their stronghold on the Cumberland, Fort Donelson. There, on Feb. 16, 1862, Grant, commanding the Army of the Tennessee, won the first great Union victory of the war, and Nashville promptly fell without a struggle.

Farther down the Tennessee, Grant was lucky to escape defeat in a bloody contest (Apr. 6?7) with Albert S. Johnston and Beauregard. Minor Union successes at Iuka (Sept. 19) and Corinth (Oct. 3?4) followed, while the counterinvasion by the Confederate Army of Tennessee under Braxton Bragg was stopped by Don Carlos Buell at Perryville, Ky. (Oct. 8, 1862). William S. Rosecrans, Buell's successor, then stalked Bragg through Tennessee, fought him to a standoff at Murfreesboro (Dec. 21, 1862?Jan. 2, 1863), and finally, by outmaneuvering him, forced the Confederate general to withdraw S of Chattanooga.

Union gunboats had cleared the upper Mississippi, leading to the fall of Memphis on June 6, 1862. Grant's Vicksburg campaign, at first stalled by the raids of Confederate cavalrymen Nathan B. Forrest and Earl Van Dorn, was pressed to a victorious end in a brilliant movement in which the navy, represented by David D. Porter, also had a hand. The Union now controlled the whole Mississippi, and the trans-Mississippi West was severed from the rest of the Confederacy. The fighting in that area had held Missouri for the Union and led to the partial conquest of Arkansas, but after the fall of Vicksburg, the war there, with the exception of the unsuccessful Union Red River expedition of Nathaniel P. Banks and a last desperate Confederate raid into Missouri by Sterling Price (both in 1864), was largely confined to guerrilla activity.

The Emancipation Proclamation
Britain never formally recognized the Confederacy (neither did France) and maintained peaceful relations with the Union despite the provocation late in 1861 of the Trent Affair, which was adroitly handled by Secretary of State Seward. Charles Francis Adams (1807?86) at London and John Bigelow at Paris were able diplomats, but probably more important in winning popular support for the Union in England and France was the Emancipation Proclamation, which Lincoln issued after Antietam.

This act appeased for a time the anti-Lincoln radical Republicans in Congress, among them Benjamin F. Wade, Zachariah Chandler, Thaddeus Stevens, and Henry W. Davis, with whom Secretary of the Treasury Salmon P. Chase and Secretary of War Edwin M. Stanton were allied. Not all Unionists were abolitionists, however, and the Emancipation Proclamation was not applied to the border slave states: Delaware, Maryland, Kentucky, and Missouri had all remained loyal. For Lincoln and kindred moderates, such as Postmaster General Montgomery Blair, the restoration of the Union, not the abolition of slavery, remained the principal objective of the war.

Turning Point
The Union victories at Gettysburg and Vicksburg in July, 1863, marked a definite turning point in the war. Both sides now had seasoned, equally valiant soldiers, and in Lee and Ulysses S. Grant each had a superior general. But the North, with its larger population and comparatively enormous industry, enjoyed a tremendous material advantage. Both sides also resorted to conscription, even though it met some resistance.

Under Stanton, successor to Simon Cameron, the overall administration of the Union army was more efficient. Problems of organization still remained, however, and Henry W. Halleck continued in the difficult role of military adviser, with the title of general in chief. The Joint Congressional Committee on the Conduct of the War, organized in Dec., 1861, attempted to influence the actions as well as the appointment of Union generals (its efforts were particularly strong on behalf of Hooker). The chairman, Benjamin F. Wade, was frequently at odds with Lincoln, and the committee's investigations and high-handed actions lowered morale among the Union forces.

Grant and Sherman
On the Georgia-Tennessee line in Sept., 1863, Bragg, having temporarily halted his retreat, severely jolted the Federals, who were saved from a complete rout by the magnificent stand of George H. Thomas, the Rock of Chickamauga. Grant, newly appointed supreme commander in the West, hurried to the scene and, with William T. Sherman, Hooker, and Thomas's fearless troops, drove Bragg back to Georgia (Nov. 25). After Knoxville, occupied in September, withstood Longstreet's siege (Nov.?Dec.), all Tennessee, hotbed of Unionism, was now safely restored to the Union.

In Mar., 1864, Lincoln, for many years an admirer of Grant, made him commander in chief. Leaving the West in Sherman's capable hands, Grant came east, took personal charge of Meade's Army of the Potomac, and engaged Lee in the Wilderness campaign (May?June, 1864). Outnumbered but still spirited, the Army of Northern Virginia was slowly and painfully forced back toward Richmond, and in July the tenacious Grant began the long siege of Petersburg.

Although Jubal A. Early won at Monocacy (July 9), threatening the city of Washington, the Confederates were unable to repeat Jackson's successful diversion of 1862, and Philip H. Sheridan, victorious in the grand manner at Cedar Creek (Oct. 19), virtually ended Early's activities in the Shenandoah Valley. For his part, Sherman, opposed first by the wily Joe Johnston and then by John B. Hood, won the Atlanta campaign (May?Sept., 1864).

The Election of 1864
On the political front, a movement within the Republican party to shelve Lincoln had collapsed as the tide turned in the Union's favor. With Andrew Johnson, Lincolm's own choice for Vice President over the incumbent Hannibal Hamlin, the President was renominated in June, 1864. The Democrats nominated McClellan, who still had a strong popular following, on an ambiguous peace platform (largely dictated by Clement L. Vallandigham, leader of the Copperheads), which the ex-general repudiated. Even so, Lincoln was easily reelected.

Lee's Surrender
After the fall of Atlanta, which had contributed to Lincoln's victory, Sherman's troops made their destructive march through Georgia. Hood had failed to draw Sherman back by invading Union-held Tennessee, and after the battle of Franklin (Nov. 30) Hood's army was almost completely annihilated by Thomas at Nashville (Dec. 15?16, 1864). Sherman presented Lincoln with the Christmas gift of Savannah, Ga., and then moved north through the Carolinas. Farragut's victory at Mobile Bay (Aug. 5, 1864) had effectively closed that port, and on Jan. 15, 1865, Wilmington, N.C., was also cut off.

After Sheridan's victory at Five Forks (Apr. 1), the Petersburg lines were breached and the Confederates evacuated Richmond (Apr. 3). With his retreat blocked by Sheridan, Lee, wisely giving up the futile contest, surrendered to Grant at Appomattox Courthouse on Apr. 9, 1865. The surviving Confederate armies also yielded when they heard of Lee's capitulation, thus ending the conflict that resulted in over 600,000 casualties.

Aftermath
The long war was over, but for the victors the peace was marred by the assassination of Abraham Lincoln, the greatest figure of the war. The ex-Confederate states, after enduring the unsuccessful attempts of Reconstruction to impose a new society on the South, were readmitted to the Union, which had been saved and in which slavery was now abolished. The Civil War brought death to more Americans than did any other war, including World War II. Photographs by Mathew B. Brady and others reveal some of the horror behind the statistics. The war cost untold billions and nourished rather than canceled hatreds and intolerance, which persisted for decades. It established many of the patterns, especially a strong central government, that are now taken for granted in American national life. Virtually every battlefield, with its graves, is either a national or a state park. Monuments commemorating Civil War figures and events are conspicuous in almost all sizable Northern towns and are even more numerous in the upper South.