Christopher was educated in the University of Cambridge. In 1572 he went to Flushing (Vlissingen), and was present at the Siege of Middelburg. Lodewijk van Boisot, the Dutch admiral, had a high opinion of his advice. Afterwards he went with one ship and a vessel of smaller size to La Rochelle to serve under Henri, Prince of Condé, who was about to send supplies to the town of Brouage, then besieged by Charles, Duke of Mayenne. Condé had intended to attack the royal fleet in person, but on the arrival of Carleill the command was given to him.