Member of Class
O 21
Boat
O 26
Sister Ships
O 21, O 22,O 23
O 24, O 25, O 26, O 27

 

O 26 under construction, 30 Apr 1940
(Photo: © Collection G.D. Horneman).
.
O 26 under construction, 30 Apr 1940

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.

1941

Exact 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.
.
A German type VII-C U-boat (left) and the U-D4 (ex-O 26). Note the German flags on the towers.

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.

 

 

 

 

 

 

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