Colonel Barry was a member of an Irish family, of which the Earls of Barrymore and Viscounts Buttevant were regarded as the heads. Barry was born in the latter part of the sixteenth century, and in his early years entered the service of the King of Spain. He was employed for a time in the Spanish fleet, and subsequently in the army of Spain in the Low Countries and Germany. Under Ambrosio Spinola, Barry distinguished himself at the Siege of Breda in 1625.