At my daughter's school, there is an exercise in general knowledge; this term's is about " The World Wars". The question posed is which abbreviation is correct, the first with Roman numerals or the second with Arabic numerals. Later, all questions use the second. I suspect the teacher is laying a trap so I want to be prepared.

While studying history. I was taught the former was correct;checking the Chicago Manual of Style, both are correct but only one choice should be used in a text. Have you all any guidance to offer? Oh, one other thing: I'm American trained but we live in Australia and the school reckons it is quite posh, in a British way.


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    The Chicago Manual of Style is right; they're both correct. The one with Roman numerals, WWII, is more common. If the teacher's laying a trap, you will have to figure it out yourself from context. Mar 17, 2013 at 13:50
  • Yes - if there is an issue with consistency, choose the consistent style. If not, choose a different quiz-setter. Having to answer in a questioner's style-of-the-moment is unfair. Wars have been fought over less. Though a Google Ngram shows that WWI is a far more commonly used variant than WW1, and WWII than WW2. Mar 17, 2013 at 15:45
  • @Peter: Does the Chicago Manual of Style actually pronounce on correctness, rather than simply advise on favoured usage? If so, one might feel the editorial staff are getting too big for their books. Mar 19, 2013 at 23:43
  • I thought it was "The War to End All Wars".
    – Hot Licks
    Oct 10, 2015 at 2:50

1 Answer 1


ODO has entries for both WWI and WWII and none for WW1 and WW2. That said, all four variations are—going by Google Ngrams—in use. But Roman numerals appear to be the preferred choice.

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