| O 26 under
construction, 30 Apr 1940 (Photo: © Collection G.D. Horneman). . |
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For more O 21 class images check out the O 21 class photo special.
1938
24 June 1938: K XXVI is ordered, but the order might still be cancelled.
8 July 1938: the order for K XXVI is now definite.
1939
20 Apr 1939: K XXVI is laid down at the R.D.M. shipyard in Rotterdam
At some stage (exact day/year unknown) during the construction the K XXVI is renamed O 26.
1940
10 May 1940: Germany attacks the Netherlands.
When the Germans invade the Netherlands, the yard personnel tries to scuttle the not yet launched O 26. Because of the unexpected and swift occupation of the Southern Maas bank, the Dutch yard personnel does not have enough time for a successful destruction of the boat.
The Germans complete the O 26 and rename her U-D4.
The Germans also captured the "getrimd diesel systeem" or "snort system" with the O 25, O 26 and O 27. The Royal Netherlands Navy was the first navy to install such a system on their submarines (O 19 and O 20).
23 Nov 1940: O 26 is launched.
1941Exact period unknown: The Germans test the snort of 'O 26'. Late 1941 the tests are broken off (against the wishes of U-Boat designer Christoph Aschmoneit) and the BdU orders the removal of the snorts of U-D3, U-D4 and U-D5.
28 Jan 1941: The U-D4 is commissioned to the German Navy.
28 Jan - Oct 1941: U-D4 is under the German command of Krvkpt. H. Brümmer-Patzig.
U-D4 is used for trials and training only, probably because of her many defects.
Jan - Apr 1941: U-D4 is attached to the 1st Flotilla in Kiel (Germany) and is used as a school boat
May - Jul. 1941: U-D4 is attached to the 3rd Flotilla in Kiel (Germany) and is used as a trial boat
Aug 1941 - Dec 1942: U-D4 is attached to the 5th Flotilla in Kiel (Germany) and is used as a school boat
Oct 1941 - Apr 1942: U-D4 is under the German command of Krvkpt. R. von Singule.
7 Dec 1941: The USA declares war on Japan after Japanese forces attack Pearl Harbour. Approximately 7 hours after the attack the Netherlands also declares war on Japan.
14 Dec 1941: Japanese planes bomb Tarempah (Anambas Islands) which is Netherlands East Indies territory.
27 Dec 1941: Japanese invaders occupy Tambelan Islands, Dutch territory, between Borneo and Singapore.
1942
Apr - May 1942: U-D4 is under the German command of Kptlt. H.O. Bernbeck.
Jun - Dec 1942: U-D4 is under the German command of Kptlt. H.O. Bernbeck.
| A German type VII-C U-boat
(left) and the U-D4
(ex-O 26). Note the German flags on the towers. According to some sources the boat on the right is U-D3 (ex-O 25) and the photo is taken in 1944 in Germany. Please contact us if you have more information on this photo. . |
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1943
Jan 1943 - Nov 1944: U-D4 is attached as a school boat to the 27th Flotilla in Gotenhafen (Germany)
Mar 1943 - Nov 1944: U-D4 is under the German command of Krvkpt. F. Schäfer.
Mid July 1943: During a tactical exercise (probably off Gotenhafen) the U-D5 practices submerged supplying from the supply U-boat U-490 .
American Navy Interrogation Report of Survivors from U-490, sunk 12 June 1944 mentions that: .....Prisoners stated that the Engineer Officer of U-490 had made a study of the problem of transferring fuel oil from one U-boat to another while submerged. During the tactical exercises in July 1943, this officer actually practiced submerged supplying from the Dutch submarine UD-5. The prisoners knew almost nothing about the procedure employed. They believed that hose and cable connections between the two boats were made on the surface. A telephone connection was then established and the boats submerged after which oil was pumped from one to the other.....
Some other sources report it was U-D4, and not U-D5.
It is reported that after U-D4 is converted to a tanker U-Boot she is used to train U-Boat crews in submerged refuelling in the Baltic. This was first practised in Sept/Oct 1943. Until the end of 1944 she is been used for about 220 submerged refuelling exercises.
Nov 1944 - Mar 1945: U-D4 is under the German command of Kptlt. F. Bart.
1944
Nov 1944 - Jan 1945: U-D4 is attached to the 24th Flotilla in Gotenhafen (Germany) and is used as a school boat.
1945
Jan - Mar 1945: U-D4 is attached to the 18th Flotilla in Hela and is used as a school boat.
19 Mar 1945: U-D4 is decommissioned.
3 May 1945: German navy personnel scuttle the U-D4 at the Kiel Arsenal (Germany).
8 May 1945: Germany surrenders.
The U-D4 wreck is broken up.
For more O 21 class images check out the O 21 class photo special.
