Military Conflict in the Civil War

By the end of this lesson, students will be able to:

• Compare the strategic strengths and weaknesses of the Union and the Confederacy in 1861, including population, industrial capacity, rail mileage, naval power, foreign-recognition prospects, and interior lines of defense.
• Account for the logic and the staged execution of the Anaconda Plan: the naval blockade, the campaign for the Mississippi River, and the eventual coordinated land invasion that compressed the Confederacy from multiple directions.
• Explain the strategic significance of the major battles of 1862 and 1863, especially First Bull Run, Antietam, Gettysburg, and Vicksburg, and the way each battle shifted the balance of the war.
• Account for the entry of roughly 180,000 Black soldiers into the Union Army through the United States Colored Troops, and explain how the Emancipation Proclamation reframed the war in ways that made European recognition of the Confederacy effectively impossible.
• Account for the total-war campaigns of Grant in Virginia and Sherman in Georgia and the Carolinas as the strategic shift that converted Union manpower and industrial advantages into Confederate surrender at Appomattox in April 1865.

The Civil War of 1861 to 1865 is the bloodiest conflict in United States history. Modern revised estimates place total deaths between roughly 620,000 and 750,000 soldiers, more than the United States lost in every other war combined through Vietnam (KC-5.3.I.A). Understanding why the Union won, why the war lasted four years, and why it ended in unconditional Confederate surrender requires an honest accounting of the strategic resources each side brought to the fight, the doctrines each side adopted, and the major battles that shifted the strategic balance.

On paper, the Union held nearly every advantage that mattered for an industrial war. The 1860 census recorded a free-state population of roughly 18.9 million against a Confederate population of about 9 million, of whom 3.5 million were enslaved and excluded from Confederate military service for most of the war. The free states held more than ninety percent of the country's manufacturing capacity, roughly seventy percent of its rail mileage, and nearly all of its small-arms factories, ironclad shipyards, and mechanized munitions production. The United States Navy stayed loyal almost in its entirety. The Confederacy began the war with no navy, no national mint, no significant arms industry, and a rail network whose multiple gauges made supply over long distances genuinely difficult.

The Confederacy's advantages were of a different kind and were real. Confederate forces fought a defensive war on interior lines, which meant they could move troops by rail between threatened points along the Atlantic and Gulf coasts faster than Union armies marching overland could compress them. Confederate political leaders only had to avoid losing; the Union had to actually conquer and hold a region the size of Western Europe. Confederate generals at the start of the war were on average more experienced field commanders than their Union counterparts; Robert E. Lee, Stonewall Jackson, James Longstreet, and Joseph E. Johnston had all been senior United States Army officers in the antebellum decade. And finally, the Confederate political class believed that European powers, especially Britain and France, would intervene diplomatically or militarily to keep the cotton supply flowing to Manchester and Lyon.

General Winfield Scott, then commanding general of the United States Army, proposed the Union's grand strategy in the spring of 1861. Newspapers nicknamed it the Anaconda Plan because it called for a slow constricting squeeze. Scott proposed a naval blockade of every Confederate port from Hampton Roads to the Rio Grande, a campaign down the Mississippi River that would split the Confederacy in two, and only then a coordinated overland invasion to compress the rebellion. Critics in 1861 mocked the plan as too slow, but the actual Union strategy that delivered victory in 1865 followed Scott's outline almost exactly. The blockade gradually choked Confederate cotton exports and arms imports; the Mississippi River campaign succeeded by the summer of 1863; and the final coordinated invasion of 1864 and 1865 by Grant and Sherman finished the work.

The first major battle of the war went the wrong way for the Union and shocked the Northern public into a longer war than anyone had expected. At First Bull Run on July 21, 1861, near Manassas, Virginia, an inexperienced Union army marched out of Washington under General Irvin McDowell and was driven from the field by Confederate forces under P.G.T. Beauregard and Joseph E. Johnston. Northern picnickers who had ridden out from Washington to watch the battle ended the day in headlong retreat with the soldiers. The defeat ended the political fantasy of a ninety-day war, produced the first call for 500,000 three-year volunteers, and brought General George B. McClellan east to organize the Army of the Potomac into the disciplined force that would actually fight the war.

The first strategic turning point came in the Eastern Theater in September 1862. Confederate General Robert E. Lee, who had taken command of the Army of Northern Virginia in June, decided to invade Maryland in the hope that a Confederate victory on Northern soil would push Britain and France toward diplomatic recognition and would shake Northern political will before the November congressional elections. The Battle of Antietam, fought on September 17, 1862, near Sharpsburg, Maryland, remains the bloodiest single day in United States military history with roughly 22,700 casualties. Tactically the battle was a draw, but Lee withdrew his army back across the Potomac, which Lincoln treated as enough of a Union victory to issue the preliminary Emancipation Proclamation five days later. The proclamation took effect on January 1, 1863, freed the enslaved population in areas still in rebellion, opened the Union ranks to Black soldiers, and effectively foreclosed European diplomatic recognition of the Confederacy by reframing the war as a war against slavery (KC-5.3.I.B). Britain, whose ruling Liberal government depended on antislavery middle-class support, would not recognize a slaveholding republic after January 1863.

The second turning point came in the first week of July 1863, in two battles fought roughly a thousand miles apart. At Gettysburg, Pennsylvania, on July 1, 2, and 3, 1863, Lee's second invasion of the North met the Army of the Potomac under General George G. Meade. The three-day battle ended with the failed frontal assault remembered as Pickett's Charge and the destruction of roughly a third of Lee's army. Lee never again invaded Northern territory. The next day, on July 4, 1863, Confederate General John C. Pemberton surrendered the fortified river town of Vicksburg, Mississippi, to Union General Ulysses S. Grant after a forty-seven-day siege. With Vicksburg in Union hands and Port Hudson surrendering nine days later, the Union held the Mississippi River from the Gulf to its source, the Confederacy was cut in two along its main interior waterway, and Grant emerged as the most successful field commander on either side of the war.

The Emancipation Proclamation also opened a manpower channel the Confederacy could not match. Roughly 180,000 Black soldiers served in segregated regiments designated United States Colored Troops, or USCT, before the war ended, along with roughly 19,000 Black sailors in the integrated Union Navy. About 40,000 USCT soldiers died, the majority from disease in the same proportions that killed white soldiers. USCT regiments fought at Port Hudson, at Fort Wagner outside Charleston where the Fifty-fourth Massachusetts made its famous assault in July 1863, at the Crater outside Petersburg in 1864, at the Battle of Nashville in December 1864, and in the Wilmington campaign in early 1865. By the end of the war, USCT regiments made up roughly ten percent of Union manpower. Their service became the decisive evidence in the political fight that produced the Fourteenth Amendment's grant of birthright citizenship.

The strategic shift to total war came in 1864 and was the doctrinal innovation of Grant and Sherman. Grant, brought east in March 1864 as general-in-chief of all Union armies, wagered that the Union could absorb the casualties of a continuous overland campaign against Lee in Virginia faster than the Confederacy could replace its own losses. The Wilderness, Spotsylvania, Cold Harbor, and the long siege of Petersburg between May 1864 and April 1865 cost both sides terribly, but the strategic arithmetic ran one way. While Grant pinned Lee in front of Petersburg, General William T. Sherman drove south from Chattanooga, took Atlanta on September 2, 1864, and then cut loose from his supply lines on November 15 for the campaign remembered as the March to the Sea. Sherman's army moved roughly 285 miles to Savannah by Christmas, destroying railroads, foundries, plantations, and food stocks across a swath of central Georgia. From Savannah, Sherman turned north into the Carolinas in early 1865, doing comparable damage to South Carolina that he held politically responsible for secession. Sherman's special order famously framed total war as a way of bringing the human cost of secession home to the civilian population that had supported it.

The political effect of total war was immediate. Atlanta's fall on September 2, 1864, almost certainly saved Lincoln's reelection in November, against a Democratic ticket led by McClellan that had run on a platform of negotiated peace. Sherman's progress through Georgia and the Carolinas demonstrated that the Confederacy could no longer protect even its core territory. Grant's pressure on Petersburg finally cracked the Confederate line on April 2, 1865; Richmond fell the next day; and on April 9, 1865, Lee surrendered the Army of Northern Virginia to Grant at Appomattox Court House, Virginia, on terms Grant deliberately framed as conciliatory. Confederate soldiers were paroled rather than imprisoned, officers retained their sidearms, and men with horses kept them for spring planting. Other Confederate forces surrendered over the following six weeks. Lincoln was assassinated by John Wilkes Booth at Ford's Theatre on April 14, 1865, five days after Appomattox, leaving the politics of Reconstruction to a vice president from Tennessee whose lenience toward the planter class would be the central fact of the next eighteen months (KC-5.3.I.D).

The human cost remade the country. The conventional figure of roughly 620,000 dead has been revised upward by demographic historians to a range between 650,000 and 750,000 once Union and Confederate disease deaths and missing-soldier records are reconciled with mortality data from the 1870 census. Two percent of the prewar population died in the war. The Confederate states lost roughly one in four of their military-age white men. Thousands of free Black families lost USCT fathers, brothers, and sons. The military-pension system that the federal government built to honor Union veterans became the largest single category of federal expenditure for the rest of the nineteenth century, and the wartime expansion of federal authority that Lesson 9 will trace was paid for, in part, by tax instruments invented to finance armies the Anaconda Plan had drawn on the map four years earlier.

Use the table below as a quick study reference. The CED does not require students to memorize a long battle list, but the AP exam frequently expects students to be able to identify the strategic significance of First Bull Run, Antietam, Gettysburg, Vicksburg, Sherman's March, and Appomattox.

The four sources below sample the war from its strategic blueprint, its bloodiest day, its second-front turning point, and the photographic record that brought combat home to the civilian public for the first time in American history.

1. (Causation) The Confederacy held genuine military advantages in 1861: interior lines of defense, more experienced senior commanders, and a war aim that required only avoiding loss. Why were those advantages insufficient to produce Confederate independence by 1865?
2. (Comparison) Compare First Bull Run in July 1861 with Antietam in September 1862. Both ended in Confederate strategic disappointment, but only one produced a major shift in Union political war aims. What accounts for the difference?
3. (Continuity and Change) Trace the Union's evolution from McClellan's cautious campaigning of 1862 to Grant's continuous overland pressure in 1864. What changed in Union doctrine, in Lincoln's political position, and in the manpower available to Union armies?
4. (Causation) The Emancipation Proclamation of January 1863 reframed the war as a struggle against slavery and opened the Union ranks to Black soldiers. How did each of those two consequences shape the strategic balance in 1863, 1864, and 1865?
5. (Comparison) Compare Sherman's Special Field Orders No. 120 with Grant's surrender terms at Appomattox. How can a single Union command apparatus produce both the doctrine of total war and a deliberately conciliatory surrender within five months of each other? What does the pairing tell you about Lincoln's strategic intent?

Draft alignment — pending educator review. AP USH codes correspond to the official College Board Course and Exam Description (Effective Fall 2023, Version 1). Statements below are paraphrased in the CountryReports voice; refer to the College Board's published CED for verbatim wording.