>>29302231/who/ has supposed to be in the Napoleonic Era from Early March. The canning is originally a quite recent thing since it was developed during the founding war. Regardless /who/'s canning is pretty mature. Rather than glass most are canned in metal cans, and it's old enough that it has became popular among civilians as well. But not all the nutrition are provided by the cans, as depicted in the lore, soldiers still rely on things the salted meat and hardtack.
