Writing 101: Capital “S”?

One of my ECW colleagues asked today whether “secession” should be capitalized or not. (For those of us who spend a lot of time editing, such questions of capitalization are important!) Here’s the rule I follow:

Normally, “secession” would be lowercase. For example, “South Carolina’s secession from the Union led the way for other states.” Or, “Edmund Ruffin advocated for secession.” That’s true if “secession” is a noun or verb.

However, according to the Oxford English Dictionary, when referring to “the withdrawal of eleven southern states from the Union in 1860, leading to the Civil War”—in other words, “secession” writ large—”Secession” gets capitalized. For example, “the Secession crisis” or “Lincoln opposed Secession.”