What conflict was characterized by a series of battles fought mainly between the Union and Confederate forces?

The Civil War, which took place from 1861 to 1865, is characterized by its extensive series of battles fought primarily between Union (Northern states) and Confederate (Southern states) forces. This conflict arose from deep-seated issues surrounding slavery, states' rights, and economic differences between the agrarian South and the industrial North. Key battles during this war included Gettysburg, Antietam, and Bull Run, highlighting the intense military engagements that shaped the nation’s history.

While the other wars mentioned involved significant conflict, they did not feature the same scale of battles specifically between two opposing factions within the United States. The Revolutionary War involved the Thirteen Colonies fighting against British rule, while the Spanish-American War was primarily driven by American expansionism and imperial interests against Spain. The War of 1812 featured conflict primarily between the United States and Great Britain, not a civil conflict within the nation itself. Thus, the distinct nature of the Civil War as an internal conflict fought predominantly through battle is what makes it the correct response to the question.