Churchill wrote in a letter to FDR just the other day that he wanted reassurance that the pens would be destroyed before being returned to the French! I guess he didn’t trust them. He easily could have thought they would go commie. They almost did several times, of course.
Notes: U-510 was of a small number of Type IXC u-boats modified for distant operations, with increased fuel, food, and enhanced AA gun armament. In 1943-1944 she conducted a patrol in the Indian Ocean, going as far east as Japanese-occupied Singapore where the Imperial Japanese navy refueled and resupplied her.
U-510 was stationed at Lorient in occupied France for most of WWII, before retreating to Flensburg in late October 1944. U-510 was at sea in the Atlantic when Germany surrendered. The crew elected not to scuttle the ship and instead proceeded to Ste. Nazaire, France where they surrendered. The Allies allocated the submarine to France as reparations.
Sometime in early 1946 the ex-U-510 was moved to Brest, France, where the French navy modified the vessel by eliminating all gun armament and adding a streamlined GUPPY-type sail, along with a new snorkel head. On 24 June 1947, the submarine was renamed Commandant Bouan and commissioned into the French navy. The French navy was fairly enthusiastic about this submarine as it had excellent range and good diving depth.
-http://harpoondatabases.com/Encyclopedia/Entry3154.aspx