When did the Civil War end? A (quick) history of America's deadliest war.

The Civil War was the deadliest conflict ever fought on American soil with approximately 620,000 fatalities, according to History.com. Recent analysis could even suggest these numbers are higher than estimated.

It is estimated there were more American military deaths in the Civil War than in World War I and World War II combined, according to figures from the National World War II Museum and Statista.

The fighting, which began in 1861, eventually ended with the original states that seceded re-joining the Union. But did you know when the Civil War actually ended? And was the final act really played out in a small town in Virginia?

When did the Civil War end?

Although Confederate Gen. Robert E. Lee surrendered to Gen. Ulysses S. Grant, the head of the Union Army, on April 9, 1865 at Appomattox Court House in Virginia, the Civil War did not end until 16 months later.

The official end came when President Andrew Johnson, who was vice president until the assassination of President Abraham Lincoln in April, declared a formal end to the war on Aug. 20th, 1866.

According to History.com and the U.S. National Archives, while Lee’s surrender was a success for the Union, the war was still not over because a great number of Confederate troops, including the second-largest army in the Confederacy, the Army of Tennessee under Gen. Joseph E. Johnston, were active even after Lee’s surrender.

Johnston and his men heard news Lee had surrendered on April 12 while they were in North Carolina. The next day, Union Gen. William T. Sherman and his men captured Raleigh, putting pressure on Johnston and pushing his men west.

Feeling the pressure, Johnston reached out to Sherman to talk about peace agreements; however, they were initially rejected by Union leaders in Washington because they gave “generous political concessions to the South.”

Confederate President Jefferson Davis ordered Johnston to continue fighting, but he refused knowing he had his back to the wall. Johnston then reached an agreement, similar to Lee’s surrender at Appomattox, with Sherman.

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What stopped the Civil War?

Johnston's surrender was the largest one in the war, giving up almost 90,000 Confederate soldiers in Florida, Georgia, North Carolina and South Carolina. As news of this surrender spread across the South, the dominos began to fall, and other Confederate soldiers began to surrender.

Fighting continued, however, west of the Mississippi River even after President Johnson had declared on May 10 that the South’s resistance “may be regarded as virtually at an end.”

Although fighting continued, on April 2, 1866, President Johnson signed a proclamation declaring the insurrection was over in all Confederate states, but Texas, which had not yet established a state government, according to History.com.

As Texas’ economy had been less impacted by the Civil War, many Confederate generals flocked to the state following the end of the conflict. These southerners, however, clashed with the large Black population in Texas, which grew during the war when southern slave owners brought enslaved Black people to Texas so they would not be captured by the Union Army, according to History.com.

President Johnson accepted the new Texas Constitution, which refused to ratify the 13th Amendment abolishing slavery because they said the abolishment of slavery was already state law. A governor for the state was elected later that year.

On Aug. 20, 1866, President Johnson acknowledged Texas’s new government and proclaimed "insurrection is at an end and that peace, order, tranquility, and civil authority now exist in and throughout the whole United States of America.”

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What started the Civil War?

The Civil War started in 1861, but years of growing tension between Southern and Northern states stemming from debates about slavery, western expansion and state’s rights had pre-dated the conflict.

In the 19th century, the U.S. experienced a period of great economic boom, but at the same time, stark divides began to grow between the economies of the North and South, according to History.com.

In the North, there was an industrialized economy that relied on manufacturing and well-established industries, while in the South, the economy was built around large scale farms, usually growing cotton or tobacco, that relied on unpaid labor from enslaved Black people.

The North’s opposition to the legalization of slavery in western territories and growing abolitionist sentiment led the South to fear slavery would be outlawed since the South heavily relied on unpaid labor from enslaved Black people for their economy, according to History.com.

The passage in 1854 of the Kansas-Nebraska Act by Congress which essentially opened up all new territories to become slave states, led to bloody conflict over this issue.

The act allowed for popular sovereignty over the decision to allow slavery in a territory or to outlaw it, which led to “Bleeding Kansas,” where pro-slavery and anti-slavery forces violently clashed over the issue.

Opposition to the Kansas-Nebraska Act led to the formation of the Republican party in the North, founded on a basis of opposing the expansion of slavery into new territories.

What is the Dred Scott case?

Tensions rose further after a 1857 Supreme Court decision in the Dred Scott case ruling slavery was legal in new territories.

In Dred Scott v. Sandford, an enslaved man, Dred Scott, had sued his master’s widow arguing he was a free man because he had been taken by his master to Wisconsin, which was a territory where slavery was prohibited, according to History.com.

The case went through the courts for a decade before getting to the U.S. Supreme Court.

On March 6, 1857, the Supreme Court, with a southern majority of justices, ruled against Scott. The decision, according to History.com, would incense abolitionists and serve as a stepping stone to the Civil War.

Why did the Confederate states want to secede?

The last straw for southern states was the election of Abraham Lincoln in 1860. Lincoln, in the new Republican party, ran on a platform of abolition, which made the South believe there was no longer a place for them in the Union.

States that had been leaning toward leaving the Union began to hold formal votes about doing so, and on Dec. 20, South Carolina became the first state to secede from the U.S. Six more states seceded by Feb. 1, 1861: Florida, Mississippi, Alabama, Louisiana, Georgia and Texas, according to PBS.

When Lincoln took power in 1861, Confederate forces were already threatening Fort Sumter in Charleston, South Carolina. On April 12, Lincoln ordered a fleet to resupply Fort Sumter, and the first shots of the Civil War were fired. North Carolina, Virginia, Arkansas and Tennessee then joined the Confederacy, according to History.com.

This article originally appeared on USA TODAY: When did the Civil War end? Quick guide to America's deadliest war.