[Ads-l] "H-Hour" and "J-Day", 21 Feb 1918

Sun Jun 8 21:33:09 UTC 2025

There was some discussion of "J-Day" and "H-Hour" here last month.  The competing theories were "J" from the French Jour and "J" in reference to "jumping off," a common military term at the time for the moment or place of launching an attack.

I thought that jumping off seems unlikely, since it would be ambiguous - as there would be a jumping off day and a jumping off hour.  Not impossible, I suppose, but it seem logically inconsistent.

Dave Wilton put together a summary of some of the early references in a post.
https://wordorigins-org.ghost.io/d-day-h-hour-j-day/

I've since done some wading through US, French and British military and historical references which suggest to me that the French likely used "Jour-J" first, which influenced the US to use "D-Day," after using "J-Day" for a brief period of time.  The British used "Z-Day" for Zero Day, for the day of the attack, and "Zero Hour" for the moment of the attack during the same period.

The earliest reference to "Jour-J" I've seen is from April 30, 1915, in an order of the French Xth Army.  It refers to J-Day and H-Hour, and to days and hours before or after H-Hour on J-Day, referred to as J-Day -1, or H-Hour +1, and the like.
Located on HathiTrust, in Les Armees Francaises dans la Grande Guerre, Volume 3, Annexes Volume 1<https://babel.hathitrust.org/cgi/pt?id=uc1.c2551766&seq=171&q1=jour+j>.

Garson O'Toole found an early example of US reference to the French planning methods in a military publication published in July 1917.  He posted it here:
https://listserv.linguistlist.org/pipermail/ads-l/2025-May/166986.html
It is in a publication called Field Artillery Notes No. 6, July 1917.  He found it on Google books, but it is also available on HathiTrust<https://babel.hathitrust.org/cgi/pt?id=mdp.39015031938122&seq=387>.

It is presented in a section relating to the use of reconnaissance photos in artillery planning.  It refers to it as the French method.  I have found no references to "D-Day" used in the US military or elsewhere before this reference.

[Excerpt]The present French method consists in issuing preliminary orders which state that on the jour "J" and at the hour "H" such and such an attack will be launched, and that previous to this day and hour the artillery preparation will be made. . . . As the preparation nears a successful conclusion, the jour "J" is announced in strictly confidential orders, but the hour "H" is never announced until every possible precaution has been taken to insure that all enemy positions and machine-gun emplacements have been destroyed.[End Excerpt]

The British forces used "Z-Day" and "zero hour" for the same purpose, as early as 1916.  The earliest I've seen is in a book on HathiTrust called History of the Great War Based on Official Documents, Military Operations France and Belgium, 1916, Sir Douglas Haig's Command to the 1st July: Battle of the Somme, Appendices, published in 1932.  It appears in an Artillery Programme of Preliminary Bombardment of the Fourth Army, dates June June 5, 1916<https://babel.hathitrust.org/cgi/pt?id=hvd.hxpq69&seq=161&q1=z+day>.

The chart uses "W" Day, "X" Day, "Y" Day, "Z" Day, for what the French would have designated Jour-J -3, Jour J -2 and Jour-J -1.  The same volume shows "zero hour" used for the moment of attack on Z-Day.

The day/letter scheme is fully explained in British instructions for an offensive in the Messines, which were collected and published in a classified document for use of the US Army War College, published in August 1917<https://babel.hathitrust.org/cgi/pt?id=hvd.32044088023619&seq=27&q1=%22z+day%22>.  The document defines days from "U" Day (five days before Z) through "C" day (three days after Z).  Any days earlier or later than those designated day names would simply be called "Z minus 6" for example, or "Z plus 4" and the like.

An order of the American First Division of the AEF<https://babel.hathitrust.org/cgi/pt?id=mdp.39015051411505&seq=325&q1=j+day>, dated February 23, 1918, refers to raids and artillery bombardments for "J-day, which will probably be fixed for February 28, 1918."

Other orders in the First Division and the Second Division, refer to "J-Day" in orders issued in April, May, June and July of 1918, for various operations.

The earliest use of "D-Day" in US military orders that I have seen are in orders of both the First Division and Second Division in early September of 1918, and in regular use following September of 1918.  British units, and American units attached to British commands continued using "Z-Day" and "zero hour" during and after September 1918.

Interestingly, in a book chronicling Operations of the 29<https://babel.hathitrust.org/cgi/pt?id=njp.32101073206292&seq=311&q1=%22d+day%22&start=1>th<https://babel.hathitrust.org/cgi/pt?id=njp.32101073206292&seq=311&q1=%22d+day%22&start=1> Division East of the Meuse River, October 8<https://babel.hathitrust.org/cgi/pt?id=njp.32101073206292&seq=311&q1=%22d+day%22&start=1>th<https://babel.hathitrust.org/cgi/pt?id=njp.32101073206292&seq=311&q1=%22d+day%22&start=1> to 30th, 1918<https://babel.hathitrust.org/cgi/pt?id=njp.32101073206292&seq=311&q1=%22d+day%22&start=1>, the records show the US using "D-Day" and the French using "Jour-J" for the same operation.  On one page they reproduce a French order of le 7 Octobre 1918 designating "Jour J=8 (huit) Octobre, Heure H=5 (cinq) heurs" and on the next page, an American order of October 7 refers to the imminent "D-Day".

The timeline, and the early US reference to the "French" method of using "Jour-J" seem to suggest that they influenced the use of "J-Day," which was later modified to D-Day for American use.  The Brits seemed to be doing their own thing the whole time.  Americans seemed to adopt "zero hour" informally, as an alternative to "H-Hour," although official orders referred to "H-Hour" in issuing orders and plans.

________________________________
From: American Dialect Society <ADS-L at LISTSERV.UGA.EDU> on behalf of Jonathan Lighter <wuxxmupp2000 at GMAIL.COM>
Sent: Monday, May 5, 2025 8:57 AM
To: ADS-L at LISTSERV.UGA.EDU <ADS-L at LISTSERV.UGA.EDU>
Subject: Re: "H-Hour" and "J-Day", 21 Feb 1918

---------------------- Information from the mail header -----------------------
Sender:       American Dialect Society <ADS-L at LISTSERV.UGA.EDU>
Poster:       Jonathan Lighter <wuxxmupp2000 at GMAIL.COM>
Subject:      Re: "H-Hour" and "J-Day", 21 Feb 1918
-------------------------------------------------------------------------------

Just to be precise, the article Stephen helpfully cites refers to an event
of May, 1918.

JL

On Mon, May 5, 2025 at 10:53=E2=80=AFAM Stephen Goranson <
0000179d4093b2d6-dmarc-request at listserv.uga.edu> wrote:

> Without denying French usage, nor speculating here now which came first,
> there are several English uses of J Day in relatively close association
> with the day of jump(ing) off.
>
> E.g., in Everybody's Magazine, vol. XXXIX no. 5, November, 1918, p.35:
>
> ..."J" day...."J" day....The men who were to fight had been brought up to
> a point near the jumping-off trench....
>
>
> https://books.google.com/books?id=3Dd2A_AQAAMAAJ&pg=3DRA4-PA35&dq=3Djump+=
off+%22J+day%22&hl=3Den&newbks=3D1&newbks_redir=3D0&sa=3DX&ved=3D2ahUKEwja9=
eDdxoyNAxUlaDABHb31Nj0QuwV6BAgGEAc#v=3Donepage&q=3Djump%20off%20%22J%20day%=
22&f=3Dfalse
>
> sg
>
> ________________________________
> From: American Dialect Society <ADS-L at LISTSERV.UGA.EDU> on behalf of
> dave at wilton.net <dave at WILTON.NET>
> Sent: Monday, May 5, 2025 10:37 AM
> To: ADS-L at LISTSERV.UGA.EDU <ADS-L at LISTSERV.UGA.EDU>
> Subject: Re: "H-Hour" and "J-Day", 21 Feb 1918
>
>
> There's "the right way, the wrong way, and the Navy way."
>
> -----Original Message-----
> From: "Jonathan Lighter" <wuxxmupp2000 at GMAIL.COM>
> Sent: Monday, May 5, 2025 8:07am
> To: ADS-L at LISTSERV.UGA.EDU
> Subject: Re: [ADS-L] "H-Hour" and "J-Day", 21 Feb 1918
>
>
>
> I've never seen a WW2 "J day" either.
>
> As you know, the date of the invasion of Okinawa (Apr. 1, 1945) was
> designated "L day," allegedly for "landing day." Just why isn't clear to
> me.
>
> JL
>
> On Mon, May 5, 2025 at 7:23=E2=80=AFAM dave at wilton.net <dave at wilton.net> =
wrote:
>
> >
> > I've seen some web articles saying J-day was used during WWII, but no
> > actual evidence provided.
> >
> > As for how widespread the AEF usage was, I also was unaware of its
> > existence. I stumbled upon it while looking for D-day/H-hour examples. =
As
> > far as I know, the usage was restricted to operations orders/plans. (I
> > tried various newspaper databases, but OCR errors made searches
> > impractical.)
> >
> >
> > -----Original Message-----
> > From: "Jonathan Lighter" <wuxxmupp2000 at GMAIL.COM>
> > Sent: Sunday, May 4, 2025 5:46pm
> > To: ADS-L at LISTSERV.UGA.EDU
> > Subject: Re: [ADS-L] "H-Hour" and "J-Day", 21 Feb 1918
> >
> >
> >
> > More interesting would be whether the U.S. army ever used "J day" again=
.
> > Long ago I read a countless number of AEF sources (admittedly mostly
> > unofficial) and don't recall ever noticing it.
> >
> > JL
> >
> > On Sun, May 4, 2025 at 1:26=E2=80=AFPM dave at wilton.net <dave at wilton.net=
> wrote:
> >
> > >
> > > I had thought of "jump off," but didn't want to bias the suggestions.
> > >
> > > But I think "jour" is more likely, and from the emails to the list,
> > > somewhat better evidenced. It makes sense that the AEF would have
> > initially
> > > adopted French terms (J =3D jour / H =3D heure), and then later trans=
lated
> > them
> > > into English. But the conclusion is speculative.
> > >
> > > -----Original Message-----
> > > From: "Peter Reitan" <pjreitan at HOTMAIL.COM>
> > > Sent: Sunday, May 4, 2025 11:47am
> > > To: ADS-L at LISTSERV.UGA.EDU
> > > Subject: Re: [ADS-L] "H-Hour" and "J-Day", 21 Feb 1918
> > >
> > >
> > >
> > > Typo. Le jour J - le jour de l'attaque.
> > >
> > >
> > >
> > > ________________________________
> > > From: American Dialect Society <ADS-L at LISTSERV.UGA.EDU> on behalf of
> > > Peter Reitan <pjreitan at HOTMAIL.COM>
> > > Sent: Sunday, May 4, 2025 7:59:25 AM
> > > To: ADS-L at LISTSERV.UGA.EDU <ADS-L at LISTSERV.UGA.EDU>
> > > Subject: Re: "H-Hour" and "J-Day", 21 Feb 1918
> > >
> > > ---------------------- Information from the mail header
> > > -----------------------
> > > Sender: American Dialect Society <ADS-L at LISTSERV.UGA.EDU>
> > > Poster: Peter Reitan <pjreitan at HOTMAIL.COM>
> > > Subject: Re: "H-Hour" and "J-Day", 21 Feb 1918
> > >
> > >
> >
> -------------------------------------------------------------------------=
------
> > >
> > > In HathiTrust archive, a 1918 French military publication uses "le
> hour j
> > > -=3D
> > > le jour de l'attaque".
> > >
> > > D'un poste de commandement. (P.C. du 21e C.A.) Bataille de l'Ailette
> (23
> > > oc=3D
> > > tobre-2 novembre 1917)
> > >
> > >
> > >
> > > ________________________________
> > > From: American Dialect Society <ADS-L at LISTSERV.UGA.EDU> on behalf of
> > > Peter =3D
> > > Reitan <pjreitan at HOTMAIL.COM>
> > > Sent: Sunday, May 4, 2025 7:41:15 AM
> > > To: ADS-L at LISTSERV.UGA.EDU <ADS-L at LISTSERV.UGA.EDU>
> > > Subject: Re: "H-Hour" and "J-Day", 21 Feb 1918
> > >
> > > ---------------------- Information from the mail header
> > > -------------------=3D
> > > ----
> > > Sender: American Dialect Society <ADS-L at LISTSERV.UGA.EDU>
> > > Poster: Peter Reitan <pjreitan at HOTMAIL.COM>
> > > Subject: Re: "H-Hour" and "J-Day", 21 Feb 1918
> > >
> > >
> >
> -------------------------------------------------------------------------=
--=3D
> > > ----
> > >
> > > They are in France, operating and planning alongside French troops, s=
o
> > > perh=3D
> > > =3D3D
> > > aps jour?
> > >
> > > ________________________________
> > > From: American Dialect Society <ADS-L at LISTSERV.UGA.EDU> on behalf of
> > > dave at w=3D
> > > =3D3D
> > > ilton.net <dave at WILTON.NET>
> > > Sent: Sunday, May 4, 2025 5:55:53 AM
> > > To: ADS-L at LISTSERV.UGA.EDU <ADS-L at LISTSERV.UGA.EDU>
> > > Subject: "H-Hour" and "J-Day", 21 Feb 1918
> > >
> > > ---------------------- Information from the mail header
> > > -------------------=3D
> > > =3D3D
> > > ----
> > > Sender: American Dialect Society <ADS-L at LISTSERV.UGA.EDU>
> > > Poster: "dave at wilton.net" <dave at WILTON.NET>
> > > Subject: "H-Hour" and "J-Day", 21 Feb 1918
> > >
> > >
> >
> -------------------------------------------------------------------------=
--=3D
> > > =3D3D
> > > ----
> > >
> > > =3D3D3D0AThe OED has 17 September 1918 for "H-Hour," but I've found t=
his
> > > from=3D
> > > 2=3D3D
> > > 1 =3D3D3D
> > > February:=3D3D3D0A =3D3D3D0AHeadquarters, 16th Infantry.
> > > =3D3D3DE2=3D3D3D80=3D3D3D9CP=3D
> > > lan for Ra=3D3D
> > > id on Rich=3D3D3D
> > > ecourt Salient.=3D3D3DE2=3D3D3D80=3D3D3D9D 21 February 1918. World Wa=
r
> Records
> > > Fi=3D
> > > rst Di=3D3D
> > > vision=3D3D3D
> > > A.E.F. Regular, vol. 10. First Division Museum. [
> > >
> https://urldefense.com/v3/__https://firstdivisionmus=3D__;!!OToaGQ!riShWf=
-ata5GLKHGTIrWpf9UoCGEjFoVCCMCZKEwFIQmvGe9SRvUYxLKcYh5iBIbu_9CJUFkKbJG$
> > > =3D3D
> > > =3D3D3D
> > >
> > >
> >
> eum.nmtvault.com/jsp/PsImageViewer.jsp?doc_id=3D3D3D3Dcdf20c52-01e6-47b0-=
ba0b=3D
> > > -6=3D3D
> > > <
> >
> https://urldefense.com/v3/__http://eum.nmtvault.com/jsp/PsImageViewer.jsp=
?doc_id=3D3D3D3Dcdf20c52-01e6-47b0-ba0b=3D-6=3D3D__;!!OToaGQ!riShWf-ata5GLK=
HGTIrWpf9UoCGEjFoVCCMCZKEwFIQmvGe9SRvUYxLKcYh5iBIbu_9CJRXjXIX1$
> > >
> > > 57=3D3D3D
> > > 4c9e5437f%2Fiwfd0000%2F20180808%2F00000002 ](
> > >
> https://urldefense.com/v3/__https://firstdivisionmuseum.n=3D__;!!OToaGQ!r=
iShWf-ata5GLKHGTIrWpf9UoCGEjFoVCCMCZKEwFIQmvGe9SRvUYxLKcYh5iBIbu_9CJQWw0jOP=
$
> > > =3D3D
> > > =3D3D3D
> > >
> > >
> >
> mtvault.com/jsp/PsImageViewer.jsp?doc_id=3D3D3D3Dcdf20c52-01e6-47b0-ba0b-=
6574=3D
> > > c9=3D3D
> > > <
> >
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id=3D3D3D3Dcdf20c52-01e6-47b0-ba0b-6574=3Dc9=3D3D__;!!OToaGQ!riShWf-ata5GLK=
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> > >
> > > e5=3D3D3D
> > > 437f%2Fiwfd0000%2F20180808%2F00000002 )[ ](
> >
> https://urldefense.com/v3/__https://firstdivisionmuseum.nm__;!!OToaGQ!riS=
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> > > =3D
> > > =3D3D
> > > =3D3D3D
> > >
> > >
> >
> tvault.com/jsp/PsImageViewer.jsp?doc_id=3D3D3D3Dcdf20c52-01e6-47b0-ba0b-6=
574c=3D
> > > 9e=3D3D
> > > <
> >
> https://urldefense.com/v3/__http://tvault.com/jsp/PsImageViewer.jsp?doc_i=
d=3D3D3D3Dcdf20c52-01e6-47b0-ba0b-6574c=3D9e=3D3D__;!!OToaGQ!riShWf-ata5GLK=
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> > >
> > > 54=3D3D3D
> > > 37f%2Fiwfd0000%2F20180808%2F00000002 )=3D3D3D0A =3D3D3D0A"Artillery: =
>From J
> > > min=3D
> > > us 5=3D3D
> > > day=3D3D3D
> > > to J day=3D3D3DE2=3D3D3D80=3D3D3D94Cutting gaps in the
> > > enemy=3D3D3DE2=3D3D3D80=3D3D3D9=3D
> > > 9s wire at p=3D3D
> > > oints other =3D3D3D
> > > than that of the real objective, namely, Salient LAHAYVILLE and Salie=
nt
> > > 252=3D
> > > =3D3D
> > > =3D3D3D
> > > 0.=3D3D3D0A=3D3D3D0A"[=3D3D3DE2=3D3D3D80=3D3D3DA6]=3D3D3D0A =3D3D3D0A=
"Box
> > Barrage=3D3D3DE2=3D
> > > =3D3D3D80=3D3D3D94A box b=3D3D
> > > arrage of 45 minutes=3D3D3D
> > > duration will be held at H hour as shown on the sketch. At H plus 25
> the
> > > b=3D
> > > =3D3D
> > > =3D3D3D
> > > ox barrage will close down to the enemy=3D3D3DE2=3D3D3D80=3D3D3D99s f=
irst
> four
> > > li=3D
> > > nes wh=3D3D
> > > ich wi=3D3D3D
> > > ll be heavily shelled till close of operation."=3D3D3D0A =3D3D3D0AI h=
ave no
> > > ide=3D
> > > a wh=3D3D
> > > at t=3D3D3D
> > > he "J" stands for. Any info or guesses are welcome.=3D3D3D0A =3D3D3D0=
AI was
> > > una=3D
> > > ble =3D3D
> > > to a=3D3D3D
> > > ntedate the OED's 7 September use of "D-Day." I think that the term m=
ay
> > > hav=3D
> > > =3D3D
> > > =3D3D3D
> > > e been introduced for this operation. (I found one relating to the sa=
me
> > > ope=3D
> > > =3D3D
> > > =3D3D3D
> > > ration in a field order of a subordinate unit dated 10 September.)
> > >
> > > ------------------------------------------------------------
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