What U.S. war ended slavery?

Why this is the answer

The Civil War ended slavery in the United States. When the war ended in 1865, the people who had been enslaved in the Southern states were freed, and later that year an amendment to the Constitution made slavery illegal in the United States. During the 1800s, Southern states came to depend on cotton and other crops sold to Europe, and landowners relied on enslaved people to do the work. As the country gained territory, many slaveholders wanted to take slavery into the new lands of the West, while most Northern states had passed laws against it. Congress passed laws to decide where slavery was legal in the West and where it was not, and each side feared the other would decide the question for the whole nation. Eleven Southern states left the Union, and in 1861 the war began. Freedom arrived in steps. In 1863 Lincoln's Emancipation Proclamation declared the enslaved people in the Confederate states free, and many of them joined the Union army. Once the war was over, all the people enslaved in the South were freed. On June 19, 1865, enslaved people in Galveston, Texas, were the last to hear the news, which is why June 19 is now the national holiday called Juneteenth. On December 6, 1865, the 13th Amendment was added to the Constitution, banning slavery and involuntary servitude everywhere in the country except as punishment for a crime. The question asks for a war, and that is where people go wrong. "The Emancipation Proclamation" and "the 13th Amendment" both have a lot to do with ending slavery, but neither is a war, so neither answers this question. And if an earlier war tempts you, remember that the people enslaved in the South were freed only after the Civil War was over. The war that split the country in two is the one that ended it.