Field Marshal George Hay, 8th Marquess of Tweeddale, was a British soldier and administrator. He served as a staff officer in the Peninsular War under Arthur Wellesley and was with Wellesley at the Second Battle of Porto when they crossed the Douro river and routed Marshal Soult's French troops in Porto. Hay also saw action at the Battle of Bussaco and at the Battle of Vitoria. He later served in the War of 1812 and commanded the 100th Regiment of Foot at the Battle of Chippawa when he was taken prisoner of war. He went on to become governor of Madras and, at the same time, Commander-in-Chief of the Madras Army, in which role he restored the discipline of the army, which had been allowed to fall into a relaxed state.

Field marshal (FM) 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 Royal Air Force (RAF). A Field Marshal's insignia consists of two crossed batons surrounded by yellow leaves below the Tudor Crown. Like Marshals of the Royal Air Force and Admirals of the Fleet, Field Marshals traditionally remain officers for life, though on half-pay when not in an appointment or retired. The rank has been used sporadically throughout its history, and was vacant during parts of the 18th and 19th centuries. After the Second World War, it became standard practice to appoint the Chief of the Imperial 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.