Port HHZ was a shore establishment of the Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 during the Second World War. It was based at Loch Cairnbawn

Loch Cairnbawn

Loch Cairnbawn or Loch a' Chàirn Bhàin is a sea inlet off Eddrachillis Bay on the west coast of the Scottish Highlands north of Ullapool. It was the site of the World War Two midget submarine training base, Port HHZ....

, Scotland

Scotland

Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

, and was established in 1942.

The base was heavily involved in the training for the X-Craft operations (Operation Source

Operation Source

Operation Source was a series of attacks to neutralise the heavy German warships – Tirpitz, Scharnhorst and Lutzow – based in northern Norway, using X-class midget submarines....

) to sink the German battleship Tirpitz

German battleship Tirpitz

Tirpitz was the second of two s built for the German Kriegsmarine during World War II. Named after Grand Admiral Alfred von Tirpitz, the architect of the Imperial Navy, the ship was laid down at the Kriegsmarinewerft in Wilhelmshaven in November 1936 and launched two and a half years later in April...

. From July 1943, the craft worked up from HMS Bonaventure

HMS Bonaventure (F139)

HMS Bonaventure was a submarine depot ship of the Royal Navy. She was initially built for civilian service with the Clan Line, but on the outbreak of the Second World War she was requisitioned by the Navy and after being launched, was converted for military service.-Construction and...

 at Port HHZ. CINCNAVHOME allowed capital ships of his fleet to act as target ships at Port HHZ. The Boom Defence organisation were also heavily involved in surrounding these ships with nets and providing net defences and equipment for the trials.

HMS Titania sailed for and arrived at Port HHZ on 30 August 1943 to act as depot ship to the submarines taking part, and the submarines HMS Thrasher

HMS Thrasher (N37)

HMS Thrasher was a T-class submarine of the Royal Navy. She was laid down by Cammell Laird & Co Limited, Birkenhead, launched in November 1940, and had an active career in the Mediterranean and Pacific Far East.-Mediterranean:...

, Truculent

HMS Truculent (P315)

HMS Truculent was a British submarine of the third group of the T class. She was built as P315 by Vickers Armstrong, Barrow, and launched on 12 September 1942.-Service:...

, Stubborn, Syrtis, Sceptre

HMS Sceptre (P215)

HMS Sceptre was a 1940-programme S-class submarine of the Royal Navy. She was launched on January 9, 1943, in Greenock, although her keel had been laid down in July 1940.-Career:...

 and Seanymph arrived between 31 August and 1 September. Special security measures at Port HHZ were increased also increased from 1 September. No leave was allowed, and only specially selected officers and ratings were permitted to leave the area. All ships present were retained in the port until the completion of the operation.