[what's up]

I thought Canada got their independence in 1867, which would mean they fought in WWI.

I could be wrong about that.

[NZerFromHK]

If we want to be absolute purists, Canada only became independent in 1931 when Britain proposed and passed the Statute of Westminster and which Canada ratified in the same year. Prior to that, Canada was a self-governing country in the British Empire - everything but foreign affairs were conducted in Ottawa yes, but foreign affairs theoretically still needed to be handled by the White Hall officials in London.

It is a bit like the relationship between Cook Islands and New Zealand today.