The Colonial Defence Committee (CDC) was a standing committee of the British Colonial Office between 1885 and 1908. During the second half of the 19th century British Army troops were being progressively withdrawn from colonial garrisons, with the intention being that colonial governments would replace them with locally raised troops. Russian victory in the 1877–1878 Russo-Turkish War led to increased concerns for the security of the British colonies and a short-term Royal Commission looked into colonial defence. It was replaced by the CDC, which first met on 22 April 1885.
One of the CDC's first actions was to ask the colonial governments to report on the condition of defences, the number of troops and quantity of stores held. Concerned about a surprise attack they also offered advice to the colonial governors as to how to prepare and respond. The CDC asked each colony to prepare a local defence plan for review by the committee. The CDC made recommendations to the governors about improvements to the plans, such a recommendation resulted in the establishment of the Hong Kong Regiment. In some cases, as in Saint Helena, where local means were not sufficient the committee drew up plans for defences which were funded by the British government. The CDC continued the policy that land-based defence was the responsibility of the colonial governments, assisted by the maritime supremacy of the Royal Navy. It also recommended the standardisation of colonial troops' equipment and training to better allow them to deploy alongside the British Army. This was not welcomed by all colonial governments, who were concerned about involvement in foreign wars. The poor performance of the army in the 1899–1902 Second Boer War led to wide-ranging defence reform, including the establishment of the Committee of Imperial Defence (CID). The CID had more senior members than the CDC and more political clout. The CDC became sidelined and was absorbed into the CID, being renamed the Overseas Defence Committee in 1908.