What U.S. war ended slavery?

Why this is the answer

The Civil War ended slavery in the United States. When the North won in 1865, all the people who had been enslaved in the Southern states were freed, and in December of that year the 13th Amendment made slavery illegal everywhere in the country. Juneteenth, June 19, marks the day in 1865 when enslaved people in Galveston, Texas, were the last to learn that they were free. Memory hook: the war that split the country is the war that ended slavery.