Britain's young men leaving (many to die) in WWI and WWII would be far closer to https://en.wikipedia.org/wiki/Emigration - not immigration.

English has many similar-looking words with very different meanings. You might want to verify your understanding with a good translation program before commenting.

I don't understand how you inferred that from the post above you, given the zero mentions of immigration.

You have a pattern of bringing up immigration in response to stories or comments that don't mention it.