In July 1914 the new German light cruiser SMS Karlsruhe was in the Caribbean in order to relieve SMS Dresden as the warship protecting German interests in Mexico, where a revolution was in progress. Her first task after the outbreak of war was to rendezvous with the liner Kronprinz Wilhelm in order to transfer guns, stores and men to her. The liner would then operate against Allied trade as an auxiliary cruiser.
At 11 am on 6 August the transfer had almost been completed when the British armoured cruiser HMS Suffolk appeared. The two German ships headed off; Suffolk pursued Karlsruhe, but was unable to catch the faster German ship. Kronprinz Wilhelm had received two 88mm guns, but only a third of the intended ammunition.
The high speed chase used up a lot of Karlsruhe’s coal, so her captain, Fregattenkapitän Erich Köhler, decided to head for Newport News in order to coal. However, at 8:30 pm in moonlight his ship spotted the British light cruiser HMS Bristol, which had already seen the German cruiser. An indecisive long range engagement followed, but Karlsruhe was out of sight by 10:30 pm.
Köhler was unable to get in touch with the supply ship Neckar, so decided to head for the Hamburg-Amerika line’s coal depot at St Thomas in the Virgin Islands. However, Karlsruhe did not have enough coal to get there, so diverted to Puerto Rico, narrowly missing the British armoured cruiser HMS Berwick during the night. She reached Puerto Rico with her bunkers almost empty.
The US authorities allowed Karlsruhe to coal, but only 800 tons were available. Köhler, concerned that his ship was being pursued by more powerful British ships, accepted what was available before sailing to the Dutch island of Curacoa for more coal.
Once Karlsruhe’s coal bunkers were full, Köhler headed for the north east coast of Brazil, which he correctly anticipated would be a safer and more lucrative area for commerce raiding. He joined up with the supply ship Patagonia en route.
Karlsruhe began operations off Brazil on 30 August. She was able to coal five times from supplies obtained from neutral ports by her supply ships or captured from British ships. She always coaled off Lavadeira Reef, which Köhler ‘considered the only suitable anchorage in that area.’
Karlsruhe captured 16 British merchantmen plus one Dutch ship that was carrying a British cargo with a total tonnage of 76,609 tons. Their value was estimated by British insurers as being well in excess of £1 million.
She retained some as supply ships, scuttling the rest. The large number of prisoners taken became a problem, so on 18 October the supply ship Crefeld was sent to neutral Tenerife with 419 prisoners. The British Official History of Seaborne Trade during the war comments that some of the prisoners later complained about their treatment, ‘but it is generally admitted that the Germans did as well as was possible in the circumstances.’
The Crefeld was due to reach Tenerife on 22 October. The prisoners would probably report Karlsruhe’s coaling base, and she had been observed by neutral ships, so Köhler decided to leave the Brazilian coast on 24 October and return to the West Indies. He intended to attack Barbados, destroying shipping in its harbour and interrupting British trade communications in the Caribbean.
Karlsruhe made the last and largest of her 17 captures on the way, the 10,328 ton liner Vandyck on 26 October. She carried 200 passengers and a large amount of stores. Late the same day, Karlsruhe stopped the British merchantman Royal Sceptre, but released her after her master persuaded the boarding officer, falsely, that her cargo was neutral.
On 4 November Karlsruhe suffered an accidental internal explosion. 262 of her crew, including Köhler, were killed, but other 146 were rescued by two of her supply ships. One of these, the Hoffnung, formerly the British Indrani, was then scuttled. The survivors managed to get back to Germany a month later via Norway on the other, the Rio Negro.
Karlsruhe was the second most successful of the five German light cruisers employed as commerce raiders, after SMS Emden. At least 26 cruisers and armed merchant cruisers took part in the search for her at different times. There were 12 cruisers and 3 armed merchant cruisers looking for her at the end of August.
The British learnt of her move away from Brazil when the prisoners from Vandyck and other prizes reached port on 2 November. However, they knew nothing of her destruction, so continued to search for her for some time. The battlecruiser HMS Princess Royal joined the search in mid-December, and reports about Karlsruhe’s alleged movements continued to be received during February and March 1915.
Kronprinz Wilhelm took 15 prizes, with a total tonnage of 60,522 tons, before 11 April 1915, when the poor state both the ship and her crew’s health forced her to enter Hampton Roads, where she was interned. She was comfortably the most successful of the five German merchant ships commissioned as commerce raiders in 1914.
 Naval Staff Monograph (Historical) ‘Review of German Cruiser Warfare 1914-1918’, p. 10. says that it was estimated that 4 tons would be left; J. S. Corbett, H. Newbolt, Naval Operations, 5 vols. (London: HMSO, 1938). vol. i, p. 50, says 12 tons were left.
 German Cruiser Warfare, pp. 1, 10.
 C. E. Fayle, Seaborne Trade, 3 vols. (London: HMSO, 1920). vol. i, p. 331.
 Ibid. p. 261, footnote 1.
 Ibid., p. 330.
 German Cruiser Warfare, p. 12.
 Ibid., pp. 1, 12.