War between the States

...Other names used by the Union side include "Great Rebellion," "War to Save the Union," "War for the Union," "War of Emancipation," and "War to Free the Slaves," while names used by the Confederate side include "Second American Revolution," "War of the Union," "War of Secession," "War of Invasion from the North," "War to Defend the Constitution," and "War Between the States." Even today, many Southerners prefer the term "War between the States."
[Cause]
The causes of the Civil War are complex, but the basics include the formation of North and South sections, the slavery debate, and the question of whether slavery should be allowed in the Western territories.

*Some of the terminology used in reference to "War between the States" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…このほか連邦側の呼び方に〈大反逆〉〈連邦を救う戦争〉〈連邦のための戦争〉〈解放戦争〉〈奴隷解放の戦争〉があり，南部連合側の呼び方には〈第2次アメリカ独立革命〉〈連合の戦争〉〈脱退戦争〉〈北部からの侵略戦争〉〈憲法擁護戦争〉〈諸州間の戦争〉などがある。今日でも南部人の多くは〈諸州間の戦争War between the States〉という表現を好む。
［原因］
　南北戦争の原因は複雑だが，その基本的なものとして，南北両セクションの形成，奴隷論争，西部領地における奴隷制度可否の問題があげられる。…

※「War between the States」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報