Steve1989, who runs a crazy MRE/ration testing channel on YouTube, laid hands on a Dec. 1906-born-on U.S. Army Emergency Ration. About the size of a large can of soup, it weighs 20-ounces and consists of bread, pemmican, and chocolate totaling about 2,000 calories if everything but the tin and paper packaging is wolfed down.
And, yes, he tastes it, and it seems to hold up to a degree. I mean for a century-old ration, anyway.
This would be the standard ration for the first part of the 20th Century and would be what the boys used in the Philipines, Pershing’s Punitive Expedition would lug around Mexico, and the earlier Doughboys take “Over There.”