Specific periods, eras, historical events, etc.: these should all be capitalized as proper nouns. Why? Since there are many periods, eras, wars, etc., the capital will differentiate the specific from the common.

Should antebellum South capitalized?

Locations. North, South, East, and West are capitalized when indicating geographical regions.

Should Southeast be capitalized?

Capitalize the traditional geographic regions in the United States: the Midwest, the North, the South, the West, and the combined regions (i.e., the Northeast, the Southeast, and the Southwest).