1 Aug, 1940
HrMs O 21 (Lt.Cdr. J.F. van Dulm) fires two torpedoes at the German submarine U-60 in the North Sea in position 55º34'N, 02º18'E. Both torpedoes missed the target. (see map)

5 Sep, 1941
HrMs O 21 (Lt.Cdr. J.F. van Dulm) torpedoes and sinks the Italian merchant Isarco (5738 GRT) about 65 nautical miles south-west of Naples, Italy in position 40º12'N, 13º17'E. (see map)

27 Sep, 1941
HrMs O 21 (Lt.Cdr. J.F. van Dulm) claims the sinking of a sailing vessel with gunfire east of Corsica in approximate position 42N, 10E.

3 Oct, 1941
HrMs O 21 (Lt.Cdr. J.F. van Dulm) torpedoes and sinks the Vichy-French merchant Qued Yquiem (1369 GRT) east of Cape Figari, Sardinia, Italy in position 40º58'N, 09º59'E. (see map)

15 Nov, 1941
While on patrol in the Tyrrhenian Sea HrMs O 21 (Lt.Cdr. J.F. van Dulm) attacks the Italian merchant Ninetto G (5335 GRT). All torpedoes fired missed their target.

16 Nov, 1941
While on patrol in the Tyrrhenian Sea HrMs O 21 (Lt.Cdr. J.F. van Dulm) attacks the Italian merchant Itu (1578 GRT). All torpedoes fired missed their target.

22 Nov, 1941
HrMs O 21 (Lt.Cdr. J.F. van Dulm) sinks the Italian fishing vessel San Salvatore (92 GRT) with gunfire in the central Tyrrhenian Sea in position 41º25'N, 10º42'E. (see map)

24 Nov, 1941
HrMs O 21 (Lt.Cdr. J.F. van Dulm) sinks the Italian sailing vessel Unione (216 GRT) with gunfire off the east coast of Sardinia, Italy in position 41º06'N, 10º02'E. (see map)

28 Nov, 1941
The German submarine U-95 was sunk in the western Mediterranean, about 100 nautical miles east-north-east of Gibraltar in position 36º24'N, 03º20'W by the Dutch submarine HrMs O 21. (Lt.Cdr. J.F. van Dulm)

More information on this encounter between these two submarines can be found on this website (offsite link). (see map)

16 Aug, 1942
While on passage from Holy Loch to Gibraltar HrMs O 21 (Lt.Cdr. J.F. van Dulm) fires torpedoes against the German submarine U-254 north-west of Cape Finisterre in approximate position 46º39'N, 12º05'W. (see map)

13 Mar, 1943
HrMs O 21. (Lt.Cdr. J.F. van Dulm) torpedoes and sinks the Japanese merchant cargo ship Kasuga Maru No.2 (3967 GRT) off Port Blair, Andaman Islands in position 11º40'N, 92º50'E. (see map)

22 Apr, 1943
HrMs O 21. (Lt.Cdr. J.F. van Dulm) torpedoes and sinks the Japanese army cargo ship Yamazato Maru (6925 GRT) in the Malacca Strait in position 03º28'N, 99º47'E. (see map)

29 Jul, 1945
HrMs O 21 (Lt.Cdr. F.J. Kroesen) damages two Japanese coasters with gunfire off the north-west coast of Java.

31 Jul, 1945
HrMs O 21. (Lt.Cdr. F.J. Kroesen) sinks a small Japanese fishing vessel with gunfire off the north-west coast of Java.