Isn't the British Army an example why an EU army actually might work. I mean, there are Welsh, Scotts and even some lost Irish in the armed forces...
You are correct, there are many
very notable Welsh, Scots and Irish members of the British Army.
However, a look through the annals of history suggests there have been a great many New Zealanders, Australians, South Africans, Canadians, Sikhs, Nepalese and other Commonwealth members of British Forces who have made significant contributions to the defence and security of both the UK and Europe. Not forgetting the Americans under their own flag.
It seems to me that Europeans continually cash cheques in words and deeds which the US, UK and Commonwealth end up guaranteeing with blood.