Which U.S. conflict was fought to determine the legality of secession and slavery?

The U.S. conflict fought to determine the legality of secession and slavery was the Civil War. This war, which lasted from 1861 to 1865, was primarily a result of tensions between the Northern states and Southern states over issues including the institution of slavery and the rights of states to secede from the Union.

The Southern states believed they had the right to secede from the Union, largely to maintain their way of life, which was heavily based on an economy supported by slave labor. Conversely, the Northern states, along with the federal government, opposed secession and aimed to preserve the Union. Ultimately, the Civil War was a significant turning point in American history, leading to the end of slavery with the passage of the 13th Amendment and affirming the principle that the Union was perpetual and that states could not unilaterally secede.

In this context, the other conflicts mentioned—World War I, the Revolutionary War, and the War of 1812—do not relate to the specific issues of secession and slavery in the same manner. World War I was primarily about global alliances and the balance of power, the Revolutionary War focused on independence from British rule, and the War of 1812 was largely