The Military Secretary is the senior military assistant to the British Secretary of State for Defence and formerly to the Secretary of State for War.

The office was created in 1795. Until 1870 the Military Secretary was the principal secretary to the Commander-in-Chief of the Forces, but in 1870 he transferred to the War Office, where he headed the Military Secretary's Division of the Military Department. The division took over some of the functions of the Central Department . It became responsible for honours, awards and brevets; appointments of colonels and appointments of officers to the staff; army establishments; cases of individual officers; general courts martial; the Honourable Corps of Gentlemen at Arms and the Yeomen of the Guard; the appointment, promotion and retirement of combatant officers; the Indian Staff Corps ; applications for direct commissions; applications for the Royal Military Academy and the Royal Military College; and the Reserve of Officers .

In 1904 the title of the Military Secretary was formally changed to Military Secretary to the Secretary of State for War. In 1964 it reverted to Military Secretary. He has usually held the rank of Major General or Lieutenant General

Military Secretaries

• Lieutenant-General Sir Philip Chetwode (1919–1920)