We give you the country of his origin, NOT the country he selflessly fought for... when he achieved his most 'kills'. Dispute all answers in the 'comments' section... if you desire. I will adjust as necessary if there are errors. All comments welcome.
I personally find writing up 'kills' as repugnant. Does an infantryman tally up the enemy soldiers he has killed with bullet, bayonet or bare hands? I would say... only in his nightmares.
The numbers in brackets next to the names are for officially recognised 'kills'. They do not include un-confirmed or 'shared kills'.