Field marshal has been the highest rank in the
British Army since 1736. A
five-star rank with
NATO code
OF-10, it is equivalent to an
admiral of the fleet in the
Royal Navy or a
marshal of the Royal Air Force in the
RAF. A field marshal's insignia consists of two crossed batons surrounded by yellow leaf below
St Edward's Crown. As with marshals of the Royal Air Force and admirals of the fleet in their respective services, field marshals remain officers of the British Army for life, though on
half-pay when not in an appointment. The rank has been used sporadically throughout its history and was vacant through parts of the eighteenth and nineteenth centuries (when all holders of the rank were deceased). After the Second World War, it became standard practice to appoint the
Chief of the Imperial General Staff (later renamed Chief of the General Staff) to the rank on his last day in the post. Army officers occupying the post of
Chief of the Defence Staff, the professional head of all British armed forces, were usually promoted to the rank upon their appointment.