KARL-FRIEDRICH MERTEN (1905 - 1993) German U-boat commander during World War II, credited with the sinking of 27 ships for a total of 170,151 gross register tons. Awarded the Knights Cross with Oak Leaves. Vintage S.P. 4" x 6" b/w, a cardstock image of the sailor half-length, likely signed during the war with rather poor contrast at the bottom of the image. Some scuffing, else very good. With: KARL DONITZ (1891-1980), German admiral who headed the U-Boat arm of the German Navy, later succeeded Hitler as Fuehrer after Hitler's suicide, S.P. 5 1/2" x 3 1/2" b/w, showing him receiving an award late in life, signed at bottom. Two pieces.