Carew was placed in the service of a French friend of his father's, but suffered demotion to muleteer and was only saved in February 1526, when a family relation, on his way to the siege of Pavia in the service of King Francis I of France, heard Carew's companions call the young man by name. On the way to the siege, the relative died and Carew took up with a marquis, who died in battle. Carew later served Philibert, Prince of Orange, after whose death he was sent by Orange's sister to King Henry VIII of England with letters in despatch; the king noted his proficiency in riding and French and took him into service.