When war was declared, the German light cruiser, SMS Köningsberg, under Captain Loof, was in Dar es Salaam and left port on 1 August 1914. She had a brief career as a commerce raider, having found a base deep in the delta of the Rufiji River at the village of Salele. On 19 September 1914, Looff heard that the cruiser HMS Pegasus was in Zanzibar Harbour repairing defects and set off to attack her. The disabled HMS Pegasus was no match for the German ship and capsized after sustaining many hits. Loof's cruiser suffered engine failure on her return from Zanzibar and he returned to his base in the Rufiji Delta, passing ten miles through the maze of islands. There he remained until he was discovered by the British cruiser HMS Chatham on the 30th October 1914. The water was too shallow for the British cruiser to pass through, and as there were four mouths of the Rufiji River Delta, a squadron of British ships, under Admiral King-Hall, was required to maintain the blockade. Aeroplanes were used to observe and bomb her but the tropical moist climate caused their glue to soften and the aeroplanes needed constant repair. In all nine aircraft were required. As the delta was too shallow to close within range of SMS Köningsberg, two shallow draft Monitors, HMS Severn and HMS Mersey were towed from Britain via Malta and were eventually able to reach the Delta and open fire on the German ship, guided by aeroplane spotting. She fired back using shore based observers for gun spotting and hit and damaged one of the 6 inch guns of HMS Mersey and holed her above the waterline. After four days repairs to HMS Mersey's gun, and tightening the strained frames and bulkheads of both Monitors, HMS Mersey and HMS Severn were able to return, anchor and continue the bombardment One of the two spotting aeroplanes was shot down by the German cruiser but the two man crew were rescued and picked up by ships boats. The monitors so damaged the German cruiser that she was scuttled by her crew, using the explosive heads of torpedoes, and she sank on the 11th July 1915 at 2.20 PM. Her surviving crew joined Lt. Colonel Lettow-Vorbeck in his East African campaign, her armament, ten 4.1 inch quick firing guns and ammunition, were taken with them and the guns were mounted on land carriages and used as mobile artillery in his campaign. Three guns have survived to this day. One gun is outside Fort Jesus at Mombasa, Kenya, mounted on its improvised gun carriage, another is outside the Union Building in Pretoria, South Africa and a third is at Jinja Barracks in Uganda
