Wednesday, January 2, 2013

The French P-38 Can Opener

The French P-38 Can Opener.
    Can opener, scraper, screwdriver, chisel, pick, the tool of a hundred thousand uses, "The Greatest Army Invention", "invented in just 30 days in the summer of 1942 by Maj. Thomas Dennehy at the Subsistence Research Laboratory in Chicago"*, was actually invented 30 years earlier by a Frenchman.
Several of my P-38s.
The two on the right are from the mid-1970's and still quite functional after 35+ years of use.
     In 1911, Etienne Marcel Darqué invented a pocket-sized can opener ("ouvre-boite") that was adopted by the French Army in the following year. Similar in appearance to the folding P-38, it was of rigid construction and was issued with a grooved wooden block to protect the user from the point on its cutting end. The weight of the opener was 15 grams (about 1/2 ounce), and the block another 15 grams. 500,000 were manufactured initially and served with the Poilu in the trenches alongside older model can openers.
Ouvre-boîte Darqué, modèle 1912
Dimensions, Ouvre-boîte Darqué, modèle 1912
But the story of Mr. Darqué's ouvre-boite does not end there. In 1913 he invented a folding version. Sacrebleu! The P-38 "John Wayne" that I had worn for so many years on my dog tag chain was not the product of American ingenuity! "How can that be?" thought I, but there it was, U.S. Patent number 1,082,800 of December 12, 1913, for E.M. Darque's "Tin Box Opener".

The folding version was apparently not adopted by the French Army, although it was manufactured in France post-WWI France for a salmon cannery in Newfoundland. In 1932, Darqué followed up with an improved version which included a blade locking device. In 1933 the patent was approved in the US as patent no. 1,921,911 and in the UK as patent GB386235(A).
Can Opener, Patent 1,921,911, August 8, 1933
     However, contrary to popular perception, the Army did not initially recognize its potential and issue the P-38 in massive quantities with canned rations. In fact, the P-38 got a somewhat slow start. The cans in C-Rations and K-Rations still utilized a steel-wire key ("sardine key") opener. Early in 1943 the K-Ration meat can was re-designed with a special light plate top "that may be opened with any knife blade, thereby dispensing with the need for a key and permitting the saving of metal used for keys.", but still retained the key through the end of the war.
Note the "key" (can opener) in the accessories section at the bottom of the illustration.
     In October 1942, it was recommended that with the initial issue of the 5-in-1 ration (so named as it was intended to feed 5 soldiers for one day) "certain can openers now on hand" (probably the P-38) were to be issued at the rate of two per vehicle. Eventually, a can opener was supplied in the main carton of each 5-in-1 ration. In May 1943, two "pocket-style can openers" (P-38's) were added to  the 10-in-1 rations.

     C-Ration cans were still manufactured with a scored key-opening band below the top of the can. This caused problems when some of  the contents of C-Ration meat unit would often spill out of the top of the can. Continued attempts at raising the band approximately 3/8 inch proved unsuccessful, as it weakened the container. "Nevertheless, the (Subsistence Research) Laboratory recommended that further efforts be made to develop a can with raised score that would withstand rough handling."; not exactly a rousing official endorsement of the P-38.
1945 C-Ration Menu 1: note the key method of opening the can.
     Meanwhile, soldiers (being pragmatic creatures) solved the problem by attacking the top of the C-Ration can with knives, bayonets, or can openers. Eventually it was determined that the most cost effective method would be to issue can openers. By the summer of 1944 an accessory pack with a can opener for the C-Ration was procured. In April 1945 the specifications for a new C-Ration were published, which incorporated the accessory packet including a "small can opener".
     Researching patents in the United States Patent and Trademark Office database for patents with "can opener" in the title from October 1940 through the end of WWII revealed that the first P-38-style can opener patent filed during this era was patent number 2,412,946, filed July 3, 1944 and approved on December 24, 1946. The patent related to improvements on existing designs, primarily in locking the blade against the body of the opener when not in use to eliminate the danger of injury to the user.
    "But", one might argue, "why would the government allow one of its officers to patent such a device, rather than throwing it out into the public domain?" There is definitely a precedent for such a patent. On October 17, 1939, in order to prevent commercial exploitation without the permission of the inventor of that culinary delight known as the D-Ration (formerly known as the "Logan Bar"), the US Government took out a patent. for  Major (later Colonel) Paul P. Logan of the Quartermaster Corps Technical Committee. Patent 2,176,086 "Concentrated Emergency Ration" was apparently filed without having to wait for approval.

      Given the P-38's ancestry and preponderance of hard evidence in Mr. Darqué's favor, I for one am convinced that Etienne Darqué is the true father of the P-38. Major Dennehy may have been the stepfather who brought it to the Subsistence Research Laboratory, but credit must certainly be given to the individual GI who truly recognized the P-38 for the great piece of equipment that it is, and for popularizing it to the point of becoming a military and cultural icon.

* The original article proclaiming Major Dennehy as the inventor of the P-38 was originally published in 1985 by Maj. Renita Foster, and reprinted in 2009 (but no sources were cited in the article). The article may be found at

QMC Historical Studies Number 6, The Development of Special Rations for the Army, September 1944
QM Corps CMH Pub 10-12-1, The Quartermaster Corps, Organization, Supply and Services, Erna Risch, US GPO, 1953.
Quartermaster Food & Container Institute for the Armed Forces, Operation Studies Number One, Volume XII, Ration Development, June 1947


  1. Fascinating ... a whole post on the simple can opener! (I'm not being sarcastic, it's very interesting and an essential piece of army gear.)

  2. Very interesting indeed!

    The P38 is a real classic, and I'm frankly surprised by its foreign origin. I still carry one today, on a daily basis, attached to my key ring, and can open a can much faster with that than with any other type of can opener.

  3. I was quite surprised myself! I stumbled on it quite by accident, when I was researching French army mess kits and accessories used in WWI.

    1. Peter, I was fascinated by your report, which I found while looking for a couple sentences of background description of the P-38 for a Vietnam book I'm working on. How did you get drawn into this curious piece of historical research? Michael Putzel

  4. Michael, Interesting question. I was researching French Army field cooking prior to and during WWI. Prior to and in the first months of WWI, the French Army (unlike most European armies) did not have rolling field kitchens. Cooking in the field was done by the squads/sections, and in addition to their individual mess kits they were issued large "marmite pots", cooking pans, coffee grinders, and can openers. The non-folding can openers were commonly found, and being a retired soldier I was intrigued by its resemblance to the P-38. I found a link to another French website for collectors of can openers. There I found the 1913 patent for the folding can opener, and investigated further. I had read the article citing Maj. Dennehy as the inventor of the P-38, but could find no corroborating evidence to back it up. Another mystery to me is where the name "P-38" actually came from. MIL-SPEC-O-20582 designates it as Opener, Can, Hand, Folding. There was not a requirement to open a can in "38 pushes" as some have insisted, only that the opener "shall completely sever the tops of circular and rectangular cans". Possibly, but this is complete speculation on my part, P-38 may have been a designation used by one or more of the manufacturers. I'd welcome any input on this. Peter

    1. The P-38 is 1.5 inches long; that is 38.1 mm. The P-51 is 2 inches long; 50.8 mm so I assume the length in mm gives rise to the nomenclature.

  5. Hello
    I am French and collector can opener. I did an article on P 38
    in my Facebook, here's the translation.'m 50 P 38 J with a list of different manufacturers and American documents on the can opener Etienne Darqué. I am also one of the first known model P 38 marked (Speaker 43/44) If you want I give you my email address.

    Regards Daniel

  6. Peter, good morning (my time). I stumbled on your blog while doing research on US Army C Rations in Vietnam for an article I am researching on the feeding of the Australian Army in Vietnam (the Oz Army was issued with a mix of Oz CR1M and US C Rations as available). I am a retired Australian Army Warrant Officer and now a full time military historian, researcher, consultant and writer. I have a long time interest in the history of military rations and military feeding and have published a major paper on the feeding of the Australian Imperial Force in the First World War. Needless to say, your blog is fascinating and hugely informative. I would like to get in contact with you privately to pick your brain about US Army rationing in Vietnam if that is possible.


    Graham Wilson

    1. Graham,
      Thank you for the kind words. Please feel free to email me at
      I should be able to help on US Army rations during Vietnam. I have been searching for more info on rations in the Australian Army, especially during the World Wars.