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

[ADSGarson O'Toole]

A 1917 document from the U.S. Army War College explained the
terminology "jour J" and "hour H". Strictly speaking, this was a blend
of French and English. The French version was "le jour J" et "l'heure
H".

Field Artillery Notes No 6
COMPILED AT THE ARMY WAR COLLEGE FROM THE LATEST AVAILABLE INFORMATION
WASHINGTON, GOVERNMENT PRINTING OFFICE, 1917
WAR DEPARTMENT, Document No 628, Office of The Adjutant General
ARTILLERY INFORMATION SERVICE

https://books.google.com/books?id=__V_6fZzDacC&pg=RA5-PA45&#v=onepage&q=%22jour%20J%22&f=false

Quote Page 11 and 12

[Begin excerpt]
Based on these the commanding general is able to make an estimate of
the progress of the preparation and thus intelligently determine upon
the "jour J" and the "hour H" which play so important a part in the
delivery of all modern attacks (See report of O 6 on Barrage and
Accompanying Fire," dated Mar. 23, 1917).
[End excerpt]

Quote Page 45

[Begin 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. The commanding general keeps in touch with
the progress of the preparation by means of aerial reconnaissances and
especially by means of aerial photographs. Firing is stopped in some
cases for 30 minutes, to allow smoke to clear away and photographs to
be taken. 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. Aerial reconnaissance and photography are kept up until the
last moment, which result in the commanding general having in his
possession photographs taken 30 minutes before his decision is made.
The hour "H" is then announced, and the attack is made according to
the preliminary orders. In this way every possible provision for
success is made.
[End excerpt]

Garson

On Thu, May 8, 2025 at 11:51 AM Stephen Goranson
<0000179d4093b2d6-dmarc-request at listserv.uga.edu> wrote:
>
> Mr. Cutchins: ...What was the jump off day?
> Mr. Withrow: We jumped off the evening of the 7th.
>
> P. 228. Alleged Executions Without Trial in France. Senate Hearings. 1923.
>
> https://books.google.com/books?id=IBUvAAAAMAAJ&pg=PA228&dq=%22jump+off+day%22&hl=en&newbks=1&newbks_redir=0&sa=X&ved=2ahUKEwin_e2fmpSNAxUW4ckDHWyYNRcQuwV6BAgFEAg#v=onepage&q=%22jump%20off%20day%22&f=false
>
> SG

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