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 the British Armed Forces, were usually promoted to the rank upon their appointment.

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