Leon Hadar, senior analyst at Wikistrat, a geostrategic consulting group, is the author of Sandstorm: Policy Failure in the Middle East.

This month Americans marked the 150-year anniversary of the Battle of Gettysburg, an event seen by many historians as a decisive victory for the Union and a turning point in the Civil War.

Indeed, hope among the leaders of the Confederacy for diplomatic recognition by Britain and other Europeans powers dissipated after the Union victory at the battle. While Great Britain remained neutral during the U.S. Civil War, Confederate leaders planned to secure independence through a strategy of drawing Britain (and France) to their side through diplomatic support and military intervention....

In a way, any British effort to end the Civil War before Gettysburg would have changed the course of that war, and, by extension, American history. In such a counterfactual scenario, there wouldn’t have been a United States. And the historical narrative of the nation (or two nations) would have been quite different from the one being taught in American schools today, which is based on the notion that the Civil War amounted to a birth of the nation and that the abolition of slavery was necessary, if not inevitable.

From that perspective, those urging that Washington use its diplomatic and military power to intervene in the civil strife engulfing the Arab World today—whether it’s the civil war in Syria or the struggle over power in Egypt—seem to assume that the historical narrative of the people of the Middle East has already been written....