nb. The following history is from different named sources and should not be taken as the "Official" history. 

In Sep 1942, the Director of Naval Intelligence authorised the formation of the Special Intelligence Unit, composed of 33 (Royal Marines) Troop, 34 (Army) Troop, 35 (RAF) Troop and 36 (Royal Navy) Troop. The Special Intelligence Unit was later renamed 30 RN Commando (Special Engineering Unit), and was redesignated 30 Assault Unit in December 1943 **.

The unit's operational role was to move ahead of advancing Allied forces, or to undertake covert infiltrations into enemy territory by land, sea or air, to capture much needed Intelligence, in the form of codes, documents, equipment or enemy personnel. The unit served in North Africa, the Greek Islands, Norway, Pantelleria, Sicily, Italy, and Corsica, 1942-1943.

In Nov 1943, 30 RN Commando returned to the UK to prepare for the Allied invasion of German occupied Europe. In Normandy, France, 30 Assault Unit (codenamed WOOLFORCE and PIKEFORCE) landed on JUNO and UTAH beaches, attempted to capture a German radar station at Douvres-la-Delivrande, and later fought their way into Cherbourg.

During July 1944 the Unit served in Rennes and Brest, and followed French forces into Paris, France, Aug 1944. In Sep 1944 30 Assault Unit began a series of operations in the Channel coast ports as they were captured by the Allies. By May 1945, Royal Marines from 30 Assault Unit had captured the German Naval Base at Bremen, Germany.

A 30 Assault Unit Royal Marines detachment was sent to the Far East in 1945, but the Japanese surrender precluded operations. Subsequent activities in Singapore, Indo-China and Hong Kong eventually provided much useful intelligence. 30 Assault Unit was finally disbanded in 1946. 

One of the documents discovered is titled "History of SigInt (Signals Intelligence) operations undertaken by 30 Commando, 30 AU", and in para 4 of that document it states " the party at Dieppe did not achieve their objectives".