Nazi U-Boat commander who was killed in 1941. Pencil signatures of Prien and his twenty six member crew of U-47 on an off-white 8.25 x 11 sheet of Hotel Kaiserhof stationery. Signatures were obtained at the reception given for them by Hitler after the sinking of the British battleship Royal Oak. Accompanied by a vintage 7 x 5 photo of Hitler and Raeder congratulating Prien and his crew at the hotel, signed in fountain pen 'Prien.' In very good condition, with scattered light wear and toning to edges, tape reinforcement to a bisecting horizontal fold and some small edge tears. RRAuction COA.