During WWI both Ukrainian and German residents were interned. The Ukrainian population in Canada is just massive so people mainly remember the Ukrainian side. Why Ukrainians? Because they were all citizens or former citizens of Austria.

What does Austria have to do with Ukrainians? Well, Austria was very big and very multi-ethinic prior to WWI. Austria contained a big chunk of what is now Western Ukraine, i.e., the parts that are predominately Ukrainian Catholic rather than the Ukrainian Orthodox norm. Eastern Austria was run by Hungary; the Hungarians were the most powerful ethnicity in Austria after the Germans and this would eventually evolve into the "Dual Monarchy" and be known as "Austria-Hungary". The Hungarians jealously guarded their #2 position by repressing the other minorities, notably the Ukrainians. There were so small pushes from the German side to create a sort of "United States of Austria" giving representation to all minority groups but these were blocked by the Hungarian side.

How did the Ukrainians get to Canada? Starting in the 1890s Ukrainians in Austria fled Hungarian oppression on mass. This was great timing as far as Canada was concerned. We had massive underpopulated areas Western Canada: what is now the prairie provinces. Canada was living under the constant American aggression: settlers coming north, rail road being run strategically close to the boarder, American politicians talking about annexing Western Canada. The prairies needed to be settled and settled quick. There was a real fear it could turn into a Texas type situation where American settlers moved in and took over with the support of the US army. Previous attempts to settle the prairies with Jews fleeing pogroms in Russia had failed miserably: these Jews had been forced to live in urban ghettos and restricted to limited urban careers for hundreds of years -- trying to turn them into peasant farmers overnight was a bad idea in hindsight; they had no farming background and very few made the transition successfully especially with how little support they were given.

At the high point, roughly half the population of the prairies were Ukrainian, especially in Alberta. Much like BC's backlashes agains Japanese/Chinese/Indian immigrants, there were big backlashes agains the Ukrainian new comers and a lot of racism directed against them. In a very similar pattern that would be repeated in BC with the Japanese in WWII, this racism was whipped up into furor during WWI and the Ukrainians had their citizenships revoked and they were removed from their lands and interned. This in spite of the fact that they had fled persecution in Austria and had no reason to love or help their former homeland. The worst part was that many Canadian soldiers of Ukrainian background fighting on the front lines in Europe found out by mail that their entire families back home had been stripped of their citizenship and land and interned. A dark moment in our history for sure.

(Side note, it was the same legislation, the Wartime Elections Act of 1917, that first granted women the vote federal that stripped Ukrainians of their citizenship. The "Famous Five" who led the suffragette movement where also staunch opponents of non-White immigration and saw their gain as a chance to take Canada back from the large number non-White immigrants to Canada: such a Ukrainians whom they considered non-White or at least not White enough. We celebrate them but brush this part under the rug.)

(Final side note, just as Vancouver is often known by the racial epitaph "Hongcouver", Edmonton is often known by the racial epitaph "Edmonchuck". "A chuck" being a racial slur against Ukrainians specifically and Eastern-Europeans generally. Much like "a honger".)

(Final final side note, of course this is a lot more complicated than I've presented here and the above has many flaws. Void in Quebec.)