Mercenary | references
one that serves merely for wages; especially a soldier hired into foreign service.
Major F.R. Burnham, upon whom the D.S.O. was recently conferred by his Majesty, is himself the King of Army Scouts... His brilliant achievements have been rewarded by his receiving a commission as Major in the British Army.
The author of these reminiscences has never renounced the American citizenship which was his by birth and parentage, yet his military title, formally confirmed by King Edward, is British.