Military service members wear two dog tags so that one can stay with the body and the other can be collected for record keeping if the person is killed in action. This system dates back to 1916, when the U.S. military first required a second disc to be suspended from the first by a short string or chain. The purpose was practical: one tag confirmed the identity of the fallen, while the other traveled with burial or medical records.
How the Two-Tag System Works
The two tags are worn on a single chain, but they serve different roles in a worst-case scenario. The longer chain (about 27 inches) holds the primary tag around the neck. The second tag hangs from a shorter chain attached to the first. If a service member is killed, one tag is removed and sent with administrative records, while the other stays with the body to ensure identification later, during recovery or burial.
Regulations on this procedure have shifted over the decades. In 1959, the military changed its rules to keep both tags with the body. By the Vietnam War, the original split system was restored: one tag removed, one tag left. That back-and-forth reflects how the military has continuously refined its casualty identification process, but the core logic of redundancy has remained the same. Two tags mean two chances to identify someone, even if one is lost, damaged, or separated from the body.
What’s Stamped on Each Tag
Both tags carry identical information. For most of military history, that meant name, Social Security number, blood type, and religious preference. The Marines add a gas mask size. The two branches also differ slightly in layout: Marine Corps tags list the last name on the first line, followed by initials and blood type on the second, with “USMC” and gas mask size on the fourth line.
In 2015, the Army made its first update to dog tags in 40 years. Social Security numbers were replaced with a 10-digit, randomly generated Department of Defense identification number. The reason was identity theft. As one Army official put it, a lost pair of dog tags with a Social Security number, blood type, name, and religion gave a stranger nearly everything needed to steal someone’s identity. The change rolled out on an as-needed basis, meaning older service members may still carry tags with their Social Security numbers until they request replacements.
The Notch Myth
If you’ve heard that the notch on older dog tags was designed to be wedged between a dead soldier’s teeth, that story is entirely false. It’s one of the most persistent myths in military culture, sometimes told with the added detail that the tag kept the mouth open to release gases from the body. Neither version is true.
The real explanation is far more mundane. Dog tags issued before 1970 had a small notch on one end called a “locating notch.” It existed because the machine used to stamp personal information onto the blank tag needed something to grip. When a soldier became a casualty, medics could place the tag into a handheld imprinting device called the Addressograph Model 70. The notch locked the tag into the correct position so the raised letters faced downward, pressing through an ink ribbon to stamp the soldier’s information onto medical paperwork. A bar inside the machine prevented full insertion unless the notch was properly aligned. After 1970, the military switched to new equipment and the notch disappeared.
The Red Medical Tag
Some service members carry a third tag: a red anodized aluminum medical warning tag. This is issued to anyone with a permanent medical condition that could compromise emergency treatment if the person were unconscious and unable to speak. Qualifying conditions include drug allergies (especially to penicillin or barbiturates), diabetes, seizure disorders, sickle cell disease, adrenal insufficiency, sensitivity to insect stings, and use of specific medications like blood thinners, corticosteroids, or insulin.
The red tag lists the patient’s name, identification number, the specific allergy or condition, and any prescribed drug therapy. It’s a different size and color from standard tags precisely so medics can spot it immediately. Someone wearing contact lenses can even be issued one, since that detail matters if a person needs emergency eye treatment or imaging.
Why Redundancy Matters
The two-tag system is ultimately about solving a problem that has haunted every military in history: unidentified dead. Before identification tags existed, Civil War soldiers sometimes pinned slips of paper with their names to their uniforms before battle, knowing the chaos of combat could leave them unrecognizable. The move to stamped metal tags, and then to a pair of them, was a direct response to that reality. Two tags mean that even if one is destroyed, buried, or lost in transit, the other preserves the connection between a body and a name.