2 Fr. dark bluish green with overprint "fortress Lorient", variety "inverted overprint", correctly franked single franking on cover from "Lorient 17 April 1945" to tepid Baule in the fortress St. Nazaire with arrival stamp from 30.4.45, between the both German Atlantic fortresses inventory from January - May 1945 a local established postal service traffic over the sea route, faultless condition, photo expertize Lothar autumn VP (2015) : "the condition is perfect. The stamps have only a very small edition from 150 piece, so they are very rare, especially inverted overprints. Covers of the fortress post Lorient are general very rare. " Michel for cover - .