Last night I was watching The Pale Blue Eye (2022), a (bad) period piece set at West Point in the year 1830. At the 21m50s mark, Captain Hitchcock (Simon McBurney) snaps at a cadet:

Effective oh-six-hundred tomorrow morning, all men will only attend class, meals, prayer services. Nothing more!

This struck me as an anachronism: I would have expected that "military time" came into use only in the age of radio and other voice-or-print telecommunications, where "8 AM" could get garbled into "8 PM" more easily than "0800" into "2000". I wouldn't have expected military time to be in use at all pre-WWI, let alone pre-Civil-War.

A cursory Google search supports that intuition. In fact there's a meme going around that says very precisely "The U.S. Army didn't officially adopt military time until 1942" — but I have no idea what the meme-maker meant by that. (Was that the date of some sort of proclamation that "from now on thou shalt always talk in hundreds"? For how long before that "official adoption," if any, was military time already in common use by ordinary soldiers and officers?)

So I'm looking for some more rigorous analysis. This is going to be tricky, since we're talking about oral language in the days before film; but maybe a military historian will know: When did the U.S. Army adopt the "oh-six-hundred" manner of speaking?

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    Also, someone in the movie said "OK", which arose around 1838, while Poe would have been of US Military Academy age in 1827-31. And did the actor (the former Dudley Dursley in the Harry Potter films) have a gentle Virginia accent? Jan 23, 2023 at 18:22
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    @AmorphousBlob Was that a Virginia accent? As a non-US person, I could only tell that it was different from everybody else's accent. And also really, really cute. Why do you so seldom hear these lovely accents in films?
    – RedSonja
    Jan 24, 2023 at 14:03
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    @AmorphousBlob Meh, lexicographers don't find the first usage ever all the time Jan 24, 2023 at 15:04
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    A "(bad) period piece" has an anachronism? How unusual ! ....actually I checked IMDB which claims it had a budget of $72M USD, so it was a well-funded production and likely had fact checking done, they just missed this one. You should add a goof to IMDB, and link it back to this post too.
    – Criggie
    Jan 24, 2023 at 22:47
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    @RedSonja, I'm definitely no expert, it just seemed vaguely but not excessively Southern to me. (Although these days, anywhere in the US a lot of people speak with a "standard" Midwestern-ish accent.) Interesting question about films... I suspect that file makers use noticeable accents to help paint a picture of the character - Daniel Craig's southern accent in the Knives Out and Glass Onion films, hard-boiled New York or Chicago cops, LA guys from the hood. Jan 25, 2023 at 15:08

2 Answers 2


The US military did not use the 24-hour clock system at the time depicted in that movie (emphasis mine).

During World War I, the British Royal Navy adopted the 24-hour clock in 1915, and the Allied armed forces followed soon after,[22] with the British Army switching officially in 1918.[24] The Canadian armed forces first started to use the 24-hour clock in late 1917.[25] In 1920, the United States Navy was the first United States organization to adopt the system; the United States Army, however, did not officially adopt the 24-hour clock until World War II, on July 1, 1942.[26]

I haven't located the original order yet, but did find mention of a training circular put out within a month, from a US Army publication from 1942. See circular #51, first on the list:

enter image description here

Another US Government document, labelled Information Digest, published on 17 June 1942 posts notice of when the US Army will start using the 24-hr clock (center paragraph): enter image description here

This confirms July 1st as starting date for the official use of the 'military time' system, for all

Official messages, dispatches, orders and reports...

How early did others adopt this system?

The above linked Wikipedia article mentions that the 24-hour clock was adopted in organizations within other nations as early as the late 19th century (Italy in 1893). None are listed as early as the 1830s:

A report by a government committee in the United Kingdom noted Italy as the first country among those mentioned to adopt 24-hour time nationally, in 1893.[22] Other European countries followed: France adopted it in 1912 (the French army in 1909), followed by Denmark (1916), and Greece (1917). By 1920, Spain, Portugal, Belgium, and Switzerland had switched, followed by Turkey (1925), and Germany (1927). By the early 1920s, many countries in Latin America had also adopted the 24-hour clock.[23] Some of the railways in India had switched before the outbreak of the war.[22]

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    You can use a 24-hour clock without saying "oh-x-hundred". Most of Europe does. There are no O's in numbers. Therefore, I see this as being only a partial answer to the question, as it does not address when this unique "oh-x-hundred" pattern of speech became popular in the US military. Jan 24, 2023 at 8:03
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    For those who are curious, like I was: "EWT" in the second screenshot stands for "Eastern War Time", which was the name used for Daylight Savings Time during WWII. Jan 24, 2023 at 15:39
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    For comparison, a BBC World Service announcer would pronounce 1930 "Nineteen Hours thirty minutes" or "Nineteen thirty". Why in the US military do they say "nineteen hundred thirty hours"? Note that the word "hundred" does not actually mean 100. It seems to be used as a separator. What is the origin of this military jargon?
    – David42
    Jan 24, 2023 at 17:30
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    @David42 Hundred is used instead of zero-zero. To avoid misunderstanding for a garbled transmission: 0616 = zero-six-sixteen. Without the zero, 'six[garbled]' it would not be clear if sixteen-something or six-something was meant. The BBC used the civilian form of the 24 hour clock system. Jan 24, 2023 at 17:47
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    @Mark Johnson Your explanation of the reason for the practice seems plausible. I chimed in because most Americans associate 24-hour time only with the military and are unaware of the civilian form. If so, they may not understand the second part of the question. I would like to hear about documentary evidence for early uses of the "hundred hours" pronunciation.
    – David42
    Jan 24, 2023 at 18:36

My grandfathers were both in wars. One in the Korean War, one in WW2. I was in Iraq and Afghanistan. None of us have ever said Oh-x-hour. It's always been zero. Like zero-6 hundred. It was used in WW1 from what I know, but wasn't made official until the 1940s. There's a movie called Zero Dark Thirty, not Oh Dark Thirty because no one says Oh Dark.

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    You imply, but don't state explicitly, that you and your grandfathers are American. As a counterexample, "Oh" is the norm in civil use in the UK, including among friends with a military background (though not in a military setting). Note that we use 24 hour clock more than in the US.
    – Chris H
    Jan 24, 2023 at 13:59
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    In US service 0 is always stated as "zero" and O is stated as 'Oh" or in the phonetic alphabet, "oscar" to strictly differentiate. If, for example, one is reading off a telephone number, e.g. 555-0009, it is read "five-five-five-zero-zero-zero-niner". This carries over into NATO usage as well, see en.wikipedia.org/wiki/NATO_phonetic_alphabet.
    – R Leonard
    Jan 24, 2023 at 15:41
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    FWIW, the Internet tells me that both "zero-six-hundred" and "oh-six-hundred" are in common colloquial/oral use, but that you're right "zero-six-hundred" would be the more "correct" form. The (unofficial?) use of "zero dark" (rather than "zero-zero hundred" or "oh-oh hundred") for "midnight" seems to be an additional epicycle on top of that. None of this explains when the "whatever-x-hundred" convention started, though. Jan 24, 2023 at 15:55
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    Do you have any sources for the use of the "hundred hours" pronunciation in World War I? Are there any training materials from World War II which describe this pronunciation?
    – David42
    Jan 24, 2023 at 18:41
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    Not sure how it is said now, but in the past, whereas the US Army might say ". . . at 0400 hours . . ." the US Navy would say ". . . at 0400 . . ." Once asked my father, a retired RADM with 33 years commissioned service why that was and he said to the effect that the Navy presumed when talking time that one could figure out "hours" all by themselves.
    – R Leonard
    Jan 24, 2023 at 21:00

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