The brigade was formed 1 September 1943 at Dorchester with personnel from 102 RM Brigade,[2] during the Second World War, with a mixture of Army Commando and Royal Marine Commando units, and was deployed to the South-East Asian Theatre of World War II to conduct operations against the invading forces of Imperial Japan, such as the Burma Campaign.

(However, the term "Commando Brigade" was often used informally, because "Special Service" was unpopular and had a superficial similarity to the name of the notorious German Schutzstaffel (SS).)

[7] However, the limited shipping capacity available at the time meant that the relocation was prolonged and the components of the brigade were not reunited until late 1944.

[8] During January 1945, the brigade was involved in the campaign to recapture Arakan, including the battles of Myebon peninsula and Kangaw.

[7] The 3rd Commando Brigade moved to secure Hong Kong – a British crown colony that was under Japanese occupation in 1941–45.

[7] During 1946, British Army personnel and units within the 3rd Commando Brigade were demobilised or transferred elsewhere and it became a Royal Marine formation.

[7] 3 Commando Brigade's most high-profile operation after the war was the Suez Crisis, when it took part in the amphibious assault against Egyptian targets.

The Iraqi Kurds had suffered immensely during the war and in its aftermath, and the brigade was used due to its rapid deployment ability.

When operating as part of the combined United Kingdom / Netherlands Landing Force, the 1st Marine Combat Group of the Dutch Korps Mariniers is also attached to the brigade.

The ATG was normally based around specialist amphibious ships, such as the former HMS Ocean, the only helicopter carrier in the British fleet until she was decommissioned and sold to Brazil in 2018.