Misinformation is incorrect or misleading information presented as fact, either intentionally or unintentionally. Disinformation is a subset of misinformation, that which is deliberately deceptive.
Yes, well in my opinion, speaking as a published researcher in mis and disinformation: I have seen better definitions, usually something to the effect where it’s false information that runs contrary to known fact at the time of the claims being made. At the time, they thought the personnel were dead.
I'm struggling to parse what you're saying: are you saying that's the definition for misinformation or disinformation? Because misinformation is a very old word that just means incorrect information [0] that sounds a lot like relatively new word [1] disinformation that means intentionally spreading misinformation.
EDIT: Just to circle back here and really make my point clear. It appears we agree that the claim is 'misinformation' because it is incorrect. But that is not what you stated in the GP comment (which is what caused me to point out the mis/dis distinction in the first place)
Disinformation is where the information being propagated is done with the intent to deceive.
Misinformation is whereby the information being propagated is not done with the intent to deceive BUT it does run counter to what is widely known as true.
The soldiers being alive, whilst being announced as dead was not done with intent to deceive (presumably), and did not run counter to widely known information, therefore it was neither disinformation nor misinformation. It was simply incorrect due to the chaos of war. Not all incorrect statements are “misinformation”.
Your definition of misinformation runs counter to almost every source I can find.
If you have a published work that makes it more clear maybe that would help, but it seems wrong that “widely known” is the litmus test, especially when, by definition, the status of those people was not widely known at the time.
It seems like your definition of “misinformation” is very susceptible to the “appeal to authority” fallacy and therefore makes it a not very useful word (i.e. does one Russian general saying something incorrect make the information not misinformation?)
EDIT: sorry to hammer the edit feature, but to that end, if more than 50% of humans believe that God punishes those who sin, does saying “God did x to punish y group” then not equate to misinformation?
