During the Spanish Civil War, the O 13 carried out convoy services to protect Dutch commercial shipping. In the May days of 1940, the O 13 was on patrol off the Dutch coast and was attacked several times by German planes. After having fled to the United Kingdom, the ship was lost during a patrol on the North Sea. It was removed from service on June 25, 1940.

• May 10-12, 1940: O 13 patrols off the Dutch coast. She is attacked by German planes several times.
• May 1940: O 13, escorted by the minesweeper Jan van Gelder, sails to the United Kingdom.
• May 12, 1940: O 13 arrives in Portsmouth (England).
• May 15 – June, 1940: O 13is based at Portsmouth and is under British operational control.
• May ??: O 13 is equipped with a loop-aerial.
• May 29 – June 1: O 13 patrols the English Channel (evacuation of Dunkirk and Bordeaux). One night, off the French coast, she encounters a German U-boat.
• June 1940: O 13 is based at Portland (England) under British operational control.
• June 5-7 June: O 13 sails to Dundee (Scotland).
• June 6/7: O 13 arrives at the King George Wharf, Dundee.
• June 11, 1940: O 13 is attached to the 9^th Flotilla in Dundee.

O 13 lost

June 12, 1940: O 13 departs for a patrol near the entrance of the Skagerrak,

Position: 57°N-05°E. The O 13 and all hands (34) are lost during the patrol.

There are three possible explanations for the loss of the O 13:

1. June 13, 1940: A German mine strikes the O 13near the Great Fisher Bank. O 13 crosses the German minefield (named 16B or 168) at approximately 56°55'N-03°40'E.
2. June 16, 1940: O 13 is bombed by two Arado type planes from the German battleship Scharnhorst. The planes reported a position 400 m north of the patrol area of O 13. It is more likely the planes attacked the British submarine Porpoise.
3. June 20, 1940, 00:25 hrs: O 13 is accidentally rammed by the Polish submarine O.R.P. Wilk, whose location was reported to be 56°50'N-03°37'E, only 16 m from the estimated position of O 13. According to details described by Wilk's XO Cdr. Romanowski in his memoirs, it is unlikely the Polish submarine rammed the O 13.

The first option seems to be the most likely.

The Hr.Ms O 13 was an O12 class submarine. It was built in 1928 and launched April 18, 1931. It entered into service on October 1, 1931.

• Dimensions: 60.4 x 6.8 x 3.6 m
• Displacement: 610 tons (above water); 754 tons (under water)
• Machine power 2 x 900 hp (diesel engine)
• 2 x 310 hp (electric motor)
• Speed 16 knots (above water) 8 knots (under water)

Armament

• 5 x 53.3 cm torpedo tube
• 2 x 44 mm machine gun
• 1 x 12.7 mm machine gun