In 1888 the explorer Ludwig Wolf and the German East Africa Company established a Forschungsstation - a research post - on the east shore of Lake Tanganyika at an elevation of 810 meters. They named the place Bismarckburg after the German chancellor. The settlement had a scientific purpose as well as a strategic one. In 1893 the ornithologist Anton Reichenow published Die Vogelfauna Der Umgegend von Bismarckburg in Berlin, a catalogue of the region's birdlife that remains a valuable source for what the lakeshore ecosystem looked like before a century of change. By 1913 the town had roughly 3,900 inhabitants, a small harbor called Wissmannhafen after the colony's first governor, and a district office that handled administration for a sprawling hinterland.

Lake Tanganyika in 1914 was patrolled by German gunboats. When war broke out in Europe, those boats started attacking British positions in Northern Rhodesia to the south. In response, the British mounted one of the stranger operations of the First World War - the Mimi and Toutou expedition, which hauled two small armed motor launches overland from South Africa, through the forests and over mountains, and launched them onto the lake at Lukuga. By May 1915 the British also had HMS Fifi and the converted vessel Vengeur. The plan was to support a land advance north from Northern Rhodesia. On 5 June 1915 the flotilla arrived off Bismarckburg. The fort looked formidable. Spicer-Simson chose discretion, pulled back to Kituta, and let the German army slip away in its dhows under cover of darkness - an escape that reportedly enraged the British army commander, Lieutenant-Colonel Murray.

When the combined British force entered Bismarckburg on 8 June 1915, the fort was empty. The guns that had deterred Spicer-Simson turned out to be logs, painted black and mounted to look convincing from a distance. The trick was classic fortress bluff, old as the idea of fortification itself, and it had just cost the British an entire enemy garrison. The German commander Paul Emil von Lettow-Vorbeck would spend another three years leading his remarkable Schutztruppe - an army of German officers and African askari soldiers - across East Africa in a running fight that never quite lost. He surrendered at nearby Abercorn in 1918, several days after the armistice in Europe, still undefeated in the field.

In 1920 the British Mandate administration of Tanganyika Territory took over, and one of its first housekeeping tasks was to strip the German names from the map. Bismarckburg became Kasanga. Wissmannhafen became Kala. The research station charter had been repealed as far back as 1894 during colonial reforms, and the town had spent most of its German decades as the headquarters of a military district. Under British rule Kasanga became quieter - a port for small steamers, a stop on the long lake route between Kigoma and the Zambian shore, and eventually a forgotten corner of what is now Tanzania's Rukwa Region.

You can still find the research station's ruins on the hillside above the lake, the stonework softened by a century of rain. The small harbor at Kala still services dhows and the occasional ferry. In 2008 the Tanzanian government announced a major investment to revamp the harbor facilities, hoping to catch trade flowing between the Congo, Zambia, and the East African coast. In 2014 planners proposed a railway branch line connecting Kasanga to the Tanzam line and, through it, to the port of Dar es Salaam. Neither project has fully arrived. But the town sits on a lake that remains one of Africa's great inland highways, and the bluff that once hid German dhows continues to watch the water. The guns are gone. Most of the wood, too. The lake keeps moving.