Image copyright Getty Images

The arrival of Pokemon Go left a baffled Canadian military struggling to understand a surge in trespassing, newly released documents show.

When the game was launched in 2016, civilians started walking and driving on to operational bases at all hours.

"Plse advise the Commissionaires that apparently Fort Frontenac is both a PokeGym and a PokeStop," one email from a major read.

"I will be completely honest in that I have no idea what that is."

The documents were released to national broadcaster CBC in response to an information request. The news organisation had spotted a criminal advisory in July 2016 - eight days after the game's release, warning police that many defence locations were "game landmarks".

Three and a half years later, the Canadian military delivered almost 500 pages of documents to CBC.

In one instance, two men drove a van into an air force base near Toronto just before midnight, CBC reports. A corporal confronted the occupants and found them playing with their smartphones. That was on July 10 - just three days after the app's release.

The game is based on catching randomly-generated pocket monsters as the player walks through the real world, and also checking into landmarks.

The problem - which became apparent shortly after launch - was that many places designated as "pokestops" or "gyms" by the app were not, in fact, public.

"There's a game out there taking off like gangbusters, and it requires people to move to digitally cached locations to get points" a colonel in Petawawa wrote, as military officials tried to understand the sudden influx of trespassers.

"The game's premise seems to be going to the 'PokeStops/Gyms' to collect 'Pokemons' (we should almost hire a 12-year-old to help us out with this)," wrote one security expert at a base in Borden - also in Ontario.

Image copyright Getty Images Image caption Despite prominent warning sign, the Borden base had to deal with overzealous gamers

In another incident, one woman was found at the Borden base playing the game while her three children climbed over tanks. Another man at the base, stopped by officers, told them: "I have to beat my kids" at the game.

As part of the military response, at least three officers at different bases were assigned the task of playing Pokemon Go on site, and logging the appearance of every gym, Pokestop, and wild monster.

But the correspondence was not all hostile. One major at Petawawa wrote that perhaps more people would visit the museum on the base.

At Halifax, in Nova Scotia, recommended that an additional Pokestop be added near the museum, and that the museum itself be upgraded to a Pokemon gym to increase footfall.

Media playback is unsupported on your device Media caption 'I lost seven stone playing Pokemon'

At the time, media reports of accidents and trespassing by players was widespread around the world.

For example, a month after the game's launch, UK police had logged hundreds of incidents involving the game - including robberies, thefts, assaults and driving offences.

One player in Wyoming discovered a dead body, while the Pentagon reportedly banned the game from government-issued phones.

In the three and a half years since the launch, player numbers have dropped considerably, but Pokemon Go retains a loyal fan base.

Some of its functionality has been integrated into the video game series that inspired it - most notably in Pokemon Let's Go, where monsters caught in the smartphone game could be transferred to the console version.