Seen above in her home port of Dar es Salaam, the cruiser SMS Königsberg began the Great War as the most powerful German warship on the Indian Ocean. Max Looff, her intrepid captain, managed to immediately evade the superior British fleet and then surprise and destroy the cruiser HMS Pegasus. But when he was forced to burn low-quality captured coal, it not only left his boilers dirty, but also caused damage to an engine piston, limiting the fast ship to just 11 knots and forcing Looff to find refuge in the ancient mangroves of the Rufiji Delta, where he has been under siege since November.

Still holding out, Looff has lost nine men to mosquito-borne diseases this Spring, with practically every man sickened; another has been eaten by a crocodile. Paul von Lettow-Vorbeck, the colonial military chief now fully in charge of the resistance in German East Africa, has pressed Looff to turn over his crew and guns to his use: “It is waste of both manpower and seapower that the last of the German cruisers, should allow herself to be immured in the jungle, when she should be fighting for the Fatherland,” Lettow-Vorbeck wrote. “I have need of these men who spend their time guarding her and have more need of her guns than this purely static operation.” But Looff comes from a proud naval tradition, so he has kept most of his men — and all his guns — on board.

Unable to escape, the Königsberg would have been a sitting duck all this time if not for the delta channels, which are too shallow for the British boats with the biggest guns. But in June the HMS Mersey and Severn, a pair of river monitors originally laid down for Brazil but appropriated for the war, arrived after being towed all the way from London. Fitted with extra armor plating, five days ago they entered the Kikunja Channel accompanied by three whalers to sweep for mines and two light cruisers, the Weymouth and Pyramus, to suppress the shore batteries Lettow-Vorbeck has set up to help protect Looff’s command.

The HMS Mersey. Like her sister ship the Severn, she has two six-inch guns that are more powerful than Looff’s 10.5 cm guns

The weapons on shore — a three-pounder cannon, a one-pounder pom-pom gun, machine guns, and snipers — are too light to do more than scratch the monitors’ added armor. But when the blockaders opened fire at 6:30 AM, the Königsberg also had spotting station on shore communicating by telephone wire to correct their aim, and was the first to score a hit one hour later. The Mersey’s forward main gun shield was split, killing four sailors and putting the weapon out of action, while she was also holed at the waterline, forcing her to fall back for several hours. Fighting strong currents to aim with consistency, the monitors also had a difficult time coordinating with their spotter aircraft, which found it hard to see the fall of shots amid the thick mangrove jungle, and scored only six hits during the day before the ebb tide forced their return through the gantlet of shore fire.

Although one the Königsberg‘s turrets was put out of action and her bridge was hit, the crew’s fire only slackened from lack of shells. Lettow-Vorbeck has endeavored to supply Looff with ammunition from a field-expedient factory set up in the railhead at Dar es Salaam, with the shells delivered overland by foot along with food, medicine, and other supplies, but Looff wanted to husband his resources. The next day, reconnaissance flights by the planes based on nearby Mafia Island confirmed that Königsberg was “still very much a fighting ship.” As a result, today the flotilla returns to finish the job with a much better appreciation for their challenges.

Battle damage visible on the Königsberg, scuttled by detonating one of the ship’s torpedoes after the fight today

Because the previous attempt suffered from the gaps between the departure of one spotter plane and the arrival of another, today’s operation is supported by two Caudron seaplanes and two Henry Farman aircraft flying from the strip on Mafia Island in shifts to ensure the flotilla is never without an observer to communicate with the monitors by Morse code. The Mersey is still short one gun, but the shore fire once again fails to penetrate her armor, and she sails ahead to draw the Königsberg’s fire. Undiverted, Looff’s gunners bracket the Severn, but a lucky near-miss by one of the second monitor’s guns destroys the telephone line and cuts the ship off from its gunnery spotters, finally giving the British Navy fire superiority.

From about 12:30, both monitors take turns shooting seventy salvos under the direction of airborne spotters, who consistently put accurate rounds on target with terrific results. Less than a half-hour later, a large explosion indicates serious damage; already wounded on the bridge, Looff continues to rally his men until he is knocked unconscious by an abdominal wound. Revived, he orders his men to scuttle the ship. A second explosion at a quarter to two in the afternoon marks the intentional detonation of a torpedo warhead, sinking the doomed Königsberg at last. Unaware of this event, the monitors maintain their rate of fire for another forty-five minutes.

By the end of the day today, thirty-three German Sailors have been killed and sixty-five wounded; the dead are buried nearby. Only a hundred men of Looff’s crew are still in fighting shape and able to march ashore, but all of the Königsberg’s guns will be salvaged and used in Lettow-Vorbeck’s campaign of resistance. For the moment, the British are content to nibble at the edges of German East Africa in a littoral campaign, but he knows they will eventually come in force, and he intends to be ready. That will be easier now that he no longer needs to keep the ship and her crew supplied by a tenuous overland route, or provide security and shore batteries.

The sunken Königsberg photographed from the air. Sinking into the mud, her upper deck will be scrapped