Seemingly out of nowhere, civilians started driving onto Canadian military bases at odd hours and wandering onto government property in July 2016, distracted by their cellphone screens. Military officials did not know what to make of it.

Pokémon Go, the augmented-reality game, had soared to the top of the download charts. Within weeks, millions of people were chasing the digital animated creatures all over the world — and going places they should not go.

More than three years later, Canadian military officials have shared internal documents with the Canadian Broadcasting Corporation News Network that show how the military, both curious and confused, reacted to the wildly popular app.

Maj. Jeff Monaghan, an official based in Kingston, Ontario, wrote in an email: “Plse advise the Commissionaires that apparently Fort Frontenac is both a Pokégym and a Pokéstop. I will be completely honest in that I have not idea what that is.”