The term originated in the British army of the eighteenth and nineteenth centuries.
If any gentlemen soldiers, or others, have a mind to serve Her Majesty, and pull down the French king; if any prentices have severe masters, any children have unnatural parents; if any servants have too little wages, or any husband too much wife; let them repair to the noble Sergeant Kite, at the Sign of the Raven, in this good town of Shrewsbury, and they shall receive present relief and entertainment.The unscrupulous methods used by some to trick the innocent have been the subject of several traditional songs composed by their victims as a warning to others, popular examples being the Irish traditional song Arthur McBride and the Scots Twa Recruiting Sergeants.
A recruit would be given the King's shilling as a mark of the contract made.
See Daily Telegraph headline The CIA is al-Qaeda's best recruiting sergeant
This United Kingdom military article is a stub.