Why are phrases like "the High Middle Ages" capitalized while e. g. "the sixth century" is not?

Is there a general rule?

  • 1
    It's probably just that there are so many centuries. Whereas the only "Ages" we normally talk about are the Middle and Dark ones (always in the plural). They're already thus "proper nouns", so by extension we usually (but by no means always) capitalise any additional sub-identifier like Early or Late. We nearly always capitalise High there because it's a slightly "exotic" word to use. Mar 14, 2012 at 1:03
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    how about the Modern era? how does that work? Mar 14, 2012 at 1:06
  • Well, it's often capitalised as you've just written it, but the modern era isn't uncommon either. And sometimes it's the Modern Era. Any given publishing house or style guide may have its preferred form, but there are no actual "rules". I'm just trying to encapsulate some kind of "reason" for the tendencies. Mar 14, 2012 at 1:17
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    Hmm, "Bronze Age" is normally capitalized, but "ancient times" is not. "The sixth century" -- no caps. "The Roaring Twenties" -- caps. I guess generic descriptions of eras are not capitalized, but things that could be considered proper names are. But in this context that's a vague criterion.
    – Jay
    Mar 14, 2012 at 6:54

1 Answer 1


In its chapter on numbers (and select other sections), the Chicago Manual of Style has these recommendations:

[9.33 Centuries] Particular centuries are spelled out and lowercased.

  • the twenty-first century
  • the eighth and ninth centuries
  • from the ninth to the eleventh century
  • the eighteen hundreds (the nineteenth century)

[9.35 Eras] Choice of the era designation depends on tradition, academic discipline, or personal preference. Chicago recommends full capitals and no periods.

[8.72 Traditional period names] Some names of periods are capitalized, either by tradition or to avoid ambiguity.

  • the Augustan Age
  • the Common Era
  • the Counter-Reformation
  • the Dark Ages
  • the Enlightenment
  • the Gay Nineties
  • the Gilded Age
  • the Grand Siècle
  • the High Middle Ages (but the early Middle Ages, the late Middle Ages)

[8.74 Historical events and programs] Names of many major historical events and programs are conventionally capitalized. Others, more recent or known by their generic descriptions, are usually lowercased. If in doubt, do not capitalize.

  • the Boston Tea Party
  • the Cold War (but a cold war, used generically)
  • the Cultural Revolution
  • The ninth century is just a century which happens to have had eight previous ones before it; the ordinal does not identify it any more uniquely than any other ordinal. By contrast, a phrase like "Dark Ages" doesn't simply refer to some ages that happened to be dark.
    – supercat
    Apr 30, 2014 at 23:28

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