Brother against brother

Civil Wars: A History in Ideas. By David Armitage. Knopf, 349 pages; $27.95. Yale University Press; £18.99.

IN DECEMBER 2011, months after fighting broke out in Syria, a State Department spokesman was asked if the conflict was really a civil war. He dodged the term, which is fraught with legal, military, political and economic implications for the intervention of outside states. Bashar al-Assad called his enemies “terrorists”. The Syrian people understood their conflict more hopefully, as a revolution (though one exile insisted to the Guardian: “This is not a revolution against a regime any more, this is a civil war.”) In July 2012, after 17,000 deaths, the Red Cross at last acknowledged that Syria was engaged in “armed conflict not of an international character”.

Civil war, writes David Armitage, a historian at Harvard University, is “an essentially contested concept about the essential elements of contestation”. Intrastate war has replaced wars between states as the most common form of organised violence: the annual average of intrastate wars between 1816 and 1989 was a tenth of the...