The war that began as a dispute over tariffs and states' rights in the U.S. was the American Civil War. The conflict stemmed from tensions over states’ rights, particularly the rights of Southern states to maintain slavery and resist federal regulations. Tariff policies that favored Northern industries over Southern agriculture also fueled discontent. The war erupted in 1861 and lasted until 1865, ultimately leading to the preservation of the Union, the abolition of slavery, and significant socioeconomic changes in the South, reshaping American society and politics for generations to come.