Defense Media Network

The P-38 Pocket Can Opener Was an Army and Marine Icon

Today, the portable Meals Ready to Eat (MRE) consumed by American ground troops come in packages that are easy to open. In times past, the rations carried by a soldier or Marine were enclosed inside steel cans. The P-38 pocket can opener of the early World War II era was the solution to opening a can of food and chowing down. Some soldiers and Marines rate the P-38 as one of the handiest inventions ever issued to troops.

While the U.S. armed forces have not issued any P-38s since the mid-1980s, some troops still carry them today. Some have been passed from one generation to the next. Many are part of collections of memorabilia belonging to veterans of past wars.

P-38 Can Opener

The P-38 can opener that many regard as an icon and symbol of an era of military life. U.S. Army photo

In 1942, the Subsistence Research Laboratory of Chicago was charged with developing a can opener. The Army’s K-ration came with a key opening system, but soldiers disliked it, and their complaints caused the Quartermaster Corps to seek an alternative. The idea was to design a device that was cheaper to make and faster to use than a standard can opener; yet was small and easily carried. The result was a small, folding can opener, the P-38. It was hinged and was just 1 and 1/2 inches long with a hole in one end. The hole was to intended for wire or string to pass through to enable a soldier to drop the can opener into boiling water for cleaning in the field. However, it also worked perfectly for hanging the P-38 on a dog tag chain.

The P-38 was first issued in 1943 as part of a ration item known as the Hospital Five-in-One. It became the standard issue item with the G-ration in June 1944. Subsequently, it was issued along with the more widely used C-Ration, which remained in inventory in the postwar era. Finally, the opener was issued in all Army field rations. The Marines picked it up and dubbed it the “John Wayne,” apparently because of its toughness or because the actor demonstrated it in a training film.

Soldiers and Marines didn’t really need to watch the film, though, because written instructions and a drawing printed on the can opener’s paper pack showed how easy it was to use.

Although “Opener, Can, Hand, Folding” is its official Army nomenclature, it soon acquired the popular name P-38. Historians disagree as to which of three theories explains the moniker. One is that soldiers called it the P-38 because it could open a can faster than the P-38 Lightning fighter plane could fly. A more likely explanation is that the “38” comes from the length of the can opener, which is 38 millimeters (or 1 1/2 inches). It also is possible that “38” was the number of punches (a “P” word) it took to open a ration can. All experts agree that P-38 did not derive its name from the Walther P-38 pistol used by the German military in World War II.

A Real Keeper

P-38 Can Opener With C-Rations

U.S. Army C-Rations. Note the P-38 can opener in the bottom left-hand corner. The P-38 was originally included in every individual ration accessory pack. U.S. Army photo

The P-38 was designed to be disposable. The Army assumed soldiers would throw them away after opening their ration cans and began putting one P-38 in every individual ration accessory pack.

But no smart soldier ever discarded his P-38. There might always arise a situation in which he might be unable to eat because he did not have a can opener. Once the Army realized that most soldiers were saving the device, it started placing fewer of them in each case of C “rats.”

Although soldiers kept the P-38 to open their rations, they also retained it because it was an invaluable field tool. According to an article by Maj. Renita Foster in the Pentagon’s newspaper in 1986, the P-38 could clean muddy boots, screw screws, open letters, strip wires, trim threads on uniforms, and sharpen pencils. The P-38 can be used to open cardboard boxes, including the cartons containing Meals Ready to Eat. Some claim that the P-38 could be used to set the points on a car engine, because the thickness of the steel was just right for the point gap.

Many a soldier hung his P-38 with his dog tags around his neck. The P-38 disappeared as an issue item in the Army, but some still carry them today, often on a key ring after acquiring it from a family member or friend or purchasing it.

The Army also developed the P-51 can opener (again, with an airplane namesake, the P-51 Mustang fighter). This was a big brother of the original, so to speak, about twice the size of a P-38 and easier to use. Mess hall cooks used it to open field ration metal pre-cooled meal trays. The P-51 can opener is fully 2 inches long, and the increased length provides greater leverage when opening cans.

Several companies are producing versions of the P-38 and P-51 can openers for civilian purchasers today.

Co-author: Fred L. Borch


Robert F. Dorr is an author, U.S. Air Force veteran, and retired American diplomat who...

    li class="comment even thread-even depth-1" id="comment-20423">
    Victor Dahlquist

    P-38 was a great tool! I kept several to share with others from C-rats.
    I was a Civ on loan so my service does not count.
    but still helping Active duty at PAFB chapel, Orlando Fl, Vietnam & all Vets museum out reach programs, Liaison Volunteer Officer for Vietnamese community so their accomplishments are seen . Was volunteer Fire-Rescue until March 2011. So try to be productive in unemployment with end of US Space program by radicals.
    Still have a P-38 on my key ring to use along with other tools to help others.

    li class="comment byuser comment-author-chuck-oldham odd alt thread-odd thread-alt depth-1" id="comment-20431">

    I used to have a P-38 on my key ring, too, but lost it to airport security back in 2001.

    li class="comment even thread-even depth-1" id="comment-20438">

    I got mine during basic training in Feb 1973,,,,and i still carry it to this day. Carlos Bazan, SFC Retired

    li class="comment odd alt thread-odd thread-alt depth-1" id="comment-20442">

    Another beautiful piece of writing, Mr. Dorr. My P-38 has been a dedicated servant for over 53 years. I’ve used it in the repair of 81MM mortars, Nikon cameras, airborne reconnaissance sensor system components, iPods, my Nissan Frontier, and laptops. I occasionally open cans with it. Its steel is superior; its blade always sharp and ready. Its motto (as mine) is Semper Fidelis!

    William Walsh
    Master Gunnery Sergeant, United States Marine Corps, Retired

    li class="comment even thread-even depth-1" id="comment-20443">

    I too am an Army verteran who has had my sare of rations opened with the P-38. However, you may have to add a paragraph to your article as it seems that the folding can opener it was a common item used by households in 1924, thus preceding the date of ‘invention’ by the Army. In this instance it is known as the can opener – key ring (top left of the page) in the following web link. Popular Mechanics. It was perhaps the Army that mass produced them for soldiers to a specification.

    li class="comment byuser comment-author-chuck-oldham odd alt thread-odd thread-alt depth-1" id="comment-20458">

    Great link and great find! Thanks for posting your comment. The P-38 certainly seems a dead ringer for the can opener illustrated. I also wanted to add that over the years I used my P-38 to open cans on several occasions when more “modern” revolving or even electric can openers couldn’t do the job.

    li class="comment even thread-even depth-1" id="comment-20487">

    I got my P38 back in 1980 when I joined the army. We were still eating the C Rations at that time. It has been the best thing I’ve ever got and I still have it to this day on my key ring. In the past I’ve had had my can openers to fail or fall apart while cooking dinner, so I would just go get my P38 and use it to finish opening a can. I’ve used it for various things over the years. Even to open my bag of MRE’s with it. It has never failed me in 32 years. I love it.

    li class="comment odd alt thread-odd thread-alt depth-1" id="comment-20495">

    Maybe just a USMC thing but we nicknamed it “John Wayne” and many a Marine could be heard asking to borrow his his buddy’s P-38 that way. Served USMC 1968 ~ 1992.

    li class="comment even thread-even depth-1" id="comment-76925">

    As a vietnam vet US Army in 1965 I wear my P38 around my neck with my dog tags.

    li class="comment odd alt thread-odd thread-alt depth-1" id="comment-77002">

    Who REALLY Invented the P-38?

    There have been can openers as long as there have been products sealed in cans. A popular topic on several web-sites and articles have profoundly claimed that the P-38 styled can opener was an Army invention. Some even proclaim it was the result of a rapid development project by an Army major.

    I doubt that the Army major invented the P-38. It seems that it was a common item used by households in 1924, thus preceding the date of ‘invention’ by the Army. Wikipedia states that this type of can opener was popular in Eastern Europe preceding 1924. Offering better evidence is an article from Popular Mechanics which depicts a P-38 styled can opener shown in a picture. This page includes several home innovations which include a “Can Opener Especially Designed for Campers and Boy Scouts, that Can Be Folded Flat and Carried on a Key Ring”.

    It was perhaps the Army that mass produced them for soldiers to a specification, which has made them popular. Also the Major may have seen a military need to provide the can opener with rations and coordinated to get them produced in quantity.

    See this link for the picture discussed above;
    Time and Money-Saving Tools For Woman’s Workshop in Home (Apr, 1924) – Source: Popular Mechanics

    li class="comment even thread-even depth-1" id="comment-119526">

    Here is my research on the history of the P-38

    li class="comment byuser comment-author-chuck-oldham odd alt thread-odd thread-alt depth-1" id="comment-119547">

    This is great stuff! Thanks for your comments and for sending this.