Seizure of the Surcouf - Operation Grasp
Unit/ Formation: Royal Marines
Location: Great Britain
Period/ Conflict: World War II
Date/s: 3 July 1940
In 1940, Surcouf was based in Cherbourg, but in May, when the Germans invaded, she was being refitted in Brest following a mission in the Antilles and Gulf of Guinea. Under command of Frigate Captain Martin, unable to dive and with only one engine functioning and a jammed rudder, she limped across the English Channel and sought refuge in Plymouth.
On 3 July, the British, concerned that the French Fleet would be taken over by the German Kriegsmarine at the French armistice, executed Operation Catapult.
The Royal Navy blockaded the harbours where French warships were anchored, and delivered an ultimatum: rejoin the fight against Germany, be put out of reach of the Germans, or scuttle.
Few accepted willingly; the North African fleet at Mers-el-Kebir and the ships based at Dakar (French West Africa) refused. The French battleships in North Africa were eventually attacked and all but one sunk at their moorings by the Mediterranean Fleet. 
'Operation Grasp' was the British seizure of French ships already in British ports including Gibraltar, Malta and Singapore or arriving in them at the time of France’s capitulation to Germany on 25 June 1940.
These ships included at Portsmouth the old battleship Courbet, the destroyer Léopard, the torpedo boats Branlebas, Cordelière, Flore, Incomprise and Melpomène, six sloops and the supply ship Pollux; at Plymouth were the old battleship Paris, the destroyers Mistral, Ouragan and Triomphant, the torpedo boat Boucher, three sloops, and the submarines Surcouf, Junon and Minerve; at Falmouth were the submarines Ondine and Orion, three sloops and the target ship Impassible; and at Dundee was the submarine Rubis.
There was resistance by the crews of Mistral and Surcouf, resulting in casualties on each side.
In addition, three minelayers, 16 submarine chasers, seven motor torpedo boats, 98 minesweepers and patrol vessels, 42 tugs and harbour craft, and 20 trawlers were seized. 
Of these boarding's the only serious incident took place at Plymouth aboard the French Submarine Surcouf, half of the boarding party made up of Royal Marines boarded from boats.
The resistance on the submarine cruiser Surcouf , at that time the largest submarine in the world and the most important French ship in England, was bloody: the French ship's command met in the officers' mess with the leader of the British boarding party, Commander Denis Sprague (commander of the Submarine Thames ), and his deputy Lieutenant Griffiths.
Capitaine Paul Martin was allowed to disembark to confer with his superior officer, Admiral Cayol , who was based on the neighboring old battleship Paris that had offered no resistance.
In the absence of the commander, the remaining crew members triggered a power failure of the lighting and tried to destroy documents and machine elements in the dark. However, the lighting was quickly switched on again.
Commander Sprague now requested the French officers to abandon ship immediately; anyone who refused would be shot. The French replied that they only obeyed orders from their commander.
Sprague hesitated, prompting one of the French officers with a hidden MAB pistol to open fire. Sprague and Griffiths were immediately mortally wounded. In the ensuing firefight in a confined space, a British seaman with a fixed bayonet killed one of the French on-board engineers and was shot in turn by the ship's doctor.
The French finally gave up in view of the hopelessness of the situation. It was the first combat action between French and British soldiers since the Battle of Waterloo 
Related Royal Marines History 'Dits'
 Wikipedia - French submarine Surcouf
 Codenames - Operations of WW2 - Operation Grasp
 IH Sutton Covert Shores - Surcouf, The Ultimate Interwar Cruiser Submarine
 Wikipedia.de - Operation Grasp