Chiefs of Staff (COS) committee

Chiefs of Staff (COS) committee, principal British inter-service body which gave advice on operational strategy to those directing the war and issued instructions to its commanders in the field when a strategy had been formulated. Once the USA entered the war the COS formed the Combined Chiefs of Staff committee with its US counterpart, the Joint Chiefs of Staff. The COS committee then became solely responsible for operational strategy in the South-East Asia Command and for Middle East Command.

Originally constituted in 1923 to co-ordinate defence and advise the Committee of Imperial Defence (CID) on strategy, the COS committee was later reinforced by two sub-committees for Joint Planning and Joint Intelligence (see UK, 8), and these remained the most important of the sub-committees which proliferated during the war years. On the outbreak of war it started reporting to the war cabinet which replaced the CID (see UK, 3). It then comprised Air Chief Marshal Newall, Admiral Pound, and Field Marshal Ironside, with Maj-General Ismay, as its secretary. Dill replaced Ironside in May 1940 and Ismay, now Chief of Staff to Churchill in his capacity as minister of defence, became Churchill's representative on the committee. Portal replaced Newall in October 1940, Brooke replaced Dill in December 1941, and Admiral Cunningham replaced Pound in October 1943. The members took turns in the chair, but after chairing it from December 1941 Brooke became its permanent chairman in March 1942.

Mountbatten, appointed adviser on Combined Operations in October 1941, attended COS meetings if Combined Operations matters were being considered, as did his successor, Maj-General Robert Laycock. But after his appointment as Chief of Combined Operations, Mountbatten became a de facto member, attending whenever ‘major issues’ or any ‘special matter’ which directly concerned him were under discussion.

When Churchill became prime minister in May 1940 he put the committee under his own control in his capacity as minister of defence, and he sometimes presided over its meetings which were held at least once daily. Committee members accompanied him to all the major Allied conferences (see Grand Alliance) and with his support and guidance they increasingly determined British strategy. In time they exerted an influence previously unsurpassed by any British military committee, and though Churchill sometimes opposed them he never overruled them. See also UK, 7.

Bibliography

Bramall, E., and and Jackson, W. , The Chiefs (London, 1991).