Brandtaucher

Brandtaucher—German for “Fire-diver”—is a submersible that holds the distinction of being the oldest known surviving submarine in the world. It was designed by Bavarian inventor and engineer Wilhelm Bauer and constructed in Kiel by Schweffel & Howaldt in 1850 for Schleswig-Holstein’s Flotilla, which was part of the Reichsflotte.

Bauer, a cavalryman during the First Schleswig War, first sketched the submarine in February 1850 as a way to break the Danish naval blockade of Germany. The idea was to attach mines to enemy hulls undetected and detonate them from a safe distance. His early drawing caught the attention of the Minister of Marine, who authorized a model measuring 70 × 18 × 29 cm. That model performed well in a demonstration in Kiel harbour before naval officials, leading to funding for a full-scale version from army personnel and local civilians.

Because funding was insufficient, the boat’s size had to be reduced and its design simplified. The planned diving depth dropped from 30 m to 9.5 m. The redesign also eliminated enclosed ballast tanks; instead, water was allowed to pool in the bottom of the hull below the main floor, where it could shift freely as the boat changed orientation. This instability likely contributed to the vessel’s loss. The control compartment was removed and replaced by a 0.5-tonne adjustable weight for trimming and a 20-tonne iron ballast keel.

As built, Brandtaucher measured 8.07 m long, 2.02 m at its widest point, and had a draught of 2.63 m. A crew of three turned large tread wheels connected to a propeller, giving the boat a speed of three knots, though it could not sustain that pace for long.

On 1 February 1851, during acceptance trials in Kiel Harbour, the submarine suffered equipment failure and sank to the bottom of a 16-metre hole. Bauer escaped by letting water in, which increased air pressure enough for him and his two companions to open the hatch and swim to the surface. This was the first witnessed and reported submarine escape.

The wreck was discovered in 1885 and raised on 5 July 1887. It was first displayed at the Naval Academy in Kiel, then moved in 1906 to the Museum für Meereskunde in Berlin. Between 1963 and 1965, it was restored in Rostock (then in the GDR) and placed on display at the Nationale Volksarmee Museum in Potsdam.