P-38 was the designation of a Lockheed fighter, but to generations of American soldiers it meant a folding steel can opener small enough to hang from a key ring or a set of dog tags. Issued with C-rations, it went from World War II through Korea and Vietnam “and into the late Cold War era,” in the words of an Army history. The Army’s own published accounts say it was developed in just 30 days in the summer of 1942 at the Subsistence Research Laboratory in Chicago.
Who did the developing depends on which Army account a reader opens, and the basic design turns out to be older than the war.
The fullest history on the Army’s website is “Mater Artium Necessitas.” The P-38!, written by retired Lt. Col. Charles “Chuck” Moody and published on army.mil on March 26, 2008. Moody wrote that the opener “was distributed with C-Rations” and that GIs carried it “from World War II through actions in Korea and Vietnam and into the late Cold War era.” His verdict on its durability: “It does not break or rust or ever need sharpening.”
Moody drew on a 1986 article by Maj. Renita Foster, which “identified 29 auxiliary uses for the ubiquitous P-38.” He added that “another soldier, Master Sergeant Steve Wilson, has compiled a list of 38 additional taskings.” Foster’s article, he wrote, gave the origin that has stuck: the P-38 “was developed in just 30 days in the summer of 1942 by the Subsistence Research Laboratory in Chicago.”
A laboratory, or Maj. Thomas Dennehy
Foster told the story herself on army.mil in an Aug. 11, 2009 piece for Fort Monmouth Public Affairs, “The best Army invention ever.” Her version names a person. “It was invented in just 30 days in the summer of 1942 by Maj. Thomas Dennehy at the Subsistence Research Laboratory in Chicago,” she wrote. Moody’s 2008 account credits the laboratory and names no individual. The two Army-published histories agree on the 30 days, the year and the lab, and differ on whether a single officer gets the credit.
Foster’s article also carries the best-known story about the name. “The P-38 acquired its infamous nomenclature from the 38 punctures around the C-ration can required for opening and the boast that it performed with the speed of the World War II P-38 fighter plane,” she wrote. That explanation is soldier lore as the Army article relays it, and no design document confirming it turned up in the sources reviewed for this article. Foster also noted that in the Navy the tool is affectionately known as the “John Wayne.”
A design older than the war
Moody did not stop at 1942. After recounting Foster’s origin story, he wrote that “the old biblical saying ‘there is no new thing under the sun’ applies to the story of the P-38,” and that “further research reveals that a longer history surrounds this workhorse tool.”
His earliest example is U.S. Patent 1,082,800. The patent record shows a “Tin-box opener” by Etienne Marcel Darque, filed on Feb. 27, 1913 and granted on Dec. 30, 1913. Moody also pointed to a 1924 Popular Mechanics illustration of a similar opener, and to two patents issued in December 1946, No. 2,412,946 to Samuel Bloomfield and No. 2,413,528 to J. W. Speaker. Moody’s point was that the 1942 opener had predecessors. His article does not dispute the account of the 30-day development in Chicago.
From C-rations to MREs
The opener outlived the ration it was made for. Foster’s 2009 article says C-rations, “tin cans filled with a variety of meats and vegetables,” have been replaced with Meals Ready To Eat. Defense Logistics Agency historian Chrissie Reilly dates the MRE to the 1980s in an April 20, 2016 DLA history of military rations, describing it as a response “to the needs of a military on the move,” designed to provide a day’s worth of sustenance in one package.
The Italian American Veterans Museum in Stone Park, Illinois, summed up the tool’s run in an April 11, 2024 article: it “became standard issue with C-Rations for the next 40 years!” Many of the soldiers in Foster’s 2009 article kept theirs on key rings and dog tags for decades. Sgt. Maj. (Ret.) Steve Wilson put it this way in her piece: “When you see a P-38 you’ve carried since the day you enlisted, it means a whole lot.”
Top image: A 1941 U.S. Army C ration B unit with its contents: biscuits, chocolate fudge, sugar and soluble coffee. Image Credit: U.S. Army — Public domain / Wikimedia Commons
This article was produced with the assistance of AI and reviewed by Combat Rated editors prior to publication.