Letter on label to reverse;
Referring to your letter of September 8, 1986, I can tell you that the Royal Danish Navy in August 1914 possesed 7 submarines; the DYKKEREN an 6 socalled “A-boats”: HAVMANDEN, THETIS, HAVFRUEN, 2DEN APRIL (former name TRITON), NAJADEN and NYMFEN.
Your boat must be one of these 6.
These boats were built 1909-1914 and were in service until 1917-1932.
During the war 1914-1918 (Denmark neutral) all 7 submarines were operational (DYKKEREN untill November 1916, when damaged after collission),