Combined Operations Headquarters[1] was a department of the British War Office set up during Second World War to harass the Germans on the European continent by means of raids carried out by use of combined naval and army forces.
The command used air and naval units to deliver the Commandos to various targets, and then recover them.
He was replaced first by Lord Louis Mountbatten, who led the command for a year.
It comprised background staff whose job was to plan operations and to develop ideas and equipment to harass the enemy in any way possible.
[1] Operations included: The Attack on the Iron Coast (film) depicts an account of Allied Combined Operations Headquarters commandos executing a daring raid on the German-occupied French coast during the Second World War.