The Directorate of Military Intelligence (DMI) was a department of the British War Office.

Over its lifetime the Directorate underwent a number of organisational changes, absorbing and shedding sections over time.

The first instance of an organisation which would later become the DMI was the Department of Topography & Statistics, formed by Major Thomas Best Jervis, late of the Bombay Engineer Corps, in 1854 in the early stages of the Crimean War.

When the War Office was subsumed into the Ministry of Defence in 1964, the DMI was absorbed into the Defence Intelligence Staff (DIS), with some functions divested elsewhere in the MoD.

Two section titles, MI5 and MI6, remain in colloquial use in the United Kingdom and elsewhere to refer to the Security Service and the Secret Intelligence Service, although neither organisation has been officially titled as such since the late 1920s.

During the First World War, British secret services were divided into numbered sections named Military Intelligence, department number x, abbreviated to MIx such as MI1 for information management.