* Notice - The Marines assigned to AEF (American Expeditionary Forces ) in France during WW1 used Army "Dod Tags" of shape "A" and "B". has authorized the use of the Marine Corps identification tag until the exhaustion of present supply, after which the tag in the Navy regulations ( tag of "C" shape ) will be used. On most examples of M-1940 USMC and USN "Dog tags" I had possibility to survey is not stamped date of Tetanus shot application, which was stamped to standard tags of "C" and "D" shape during WW2 and thus these tags should be post or very late WW2 issue.
In the inter war period and at the beginning of the WW2 the dog tags were not standard issue. ID tags will be issued "in the time of war or other national emergency ....". After war M-1940 tag continuously replaced the tags of "C" and "D" shape.
The tags was made of monel metal which was a corrosion resistant nickel alloy containing copper, iron and manganese. This General Order was amended in 1917 which resulted in a second identical dog tag to be suspended with a short piece of cord directly below the first tag.
Dog tags are usually fabricated from a corrosion-resistant metal. Dog tags first appeared on the scene during the Civil War. During my 20 years in the Army, they were always referred to as "dog tags".The signaculum was a pendant-like object made out of lead and was to be worn around their neck.The signaculum would have their name etched on it as well as other information like legion they belonged to and start date of service.