After the crushing victory over the French and British armies in France in May/June 1940, the German High Command started working out how to launch a successful land invasion of the English mainland, which was given the codename “Operation Sealion”.
One of the key elements of the plan was the need for the Wehrmacht infantry to have armoured support as they landed on the English coast. The preferred solution was for tanks to be taken close to the British coast on specially adapted ships, and then lowered into the sea. They would then drive along the seabed before emerging on the invasion beaches. The Tauchpanzer (diving tank) would be able to operate underwater for up to twenty minutes, and thus provide the support required to make a landing on the coast a success. 168 Pz IIIs were modified this way, along with 42 PZ IV tanks.
The Tauchpanzer was produced by sealing all openings on the tank using a waterproof compound. The gap between the turret and the hull was closed with an inflatable rubber ring, while rubber sheeting covered the commander’s cupola, the mantlet and the hull machine gun. The engine intakes were blocked with rubber seals, while the exhaust stacks were given non-return valves to prevent water reaching the engine that way. The rubber seals were fitted with explosive charges to allow them to be removed from inside the tank. In case the waterproofing failed the tanks were equipped with pumps.
Air was supplied by an 18m long flexible hose, attacked to a buoy floating on the surface, with a 1.50m air intake stack above the buoy. Maximum operating depth was 15m, and the tank was designed to stay underwater for no more than twenty minutes.
From July 1940, four sections of volunteers from existing Panzer regiments were trained on the island of Sylt, and then for further training at the Panzer training centre at Putlos in early August. Their use in Operation Sealion never occurred, due to the failure of the Luftwaffe to gain air superiority in the Battle of Britain.
The idea of using submersible tanks was not shelved, so in early 1941 the Tauchpaners were modified. The long hose was replaced by a shorter 3.5 metre snorkel, to adapt them for river crossings with a maximum depth of 5 metres.
Tauchpanzer IIIs and IVs were used during Operation Barbarossa, the invasion of the USSR on the 22nd of June 1941, in service with 6th Panzer Regiment, 3rd Panzer Division, and 18th Panzer Regiment, 18th Panzer Division. It was he 18th Panzer Regiment under Major Manfred Graf von Strachwitz that used the Tauchpanzers to cross the River Bug at Patulin, after which they were used as normal tanks. This was the only occasion when Tauchpanzers were used in combat during the Second World War.
The Tauchpanzer demonstrated a very different approach to the problem of supporting amphibious operations to that adopted by the Allies in 1944 for the D-Day landings in Normandy – rather than produce submersible tanks, the British and Americans concentrated on making their tanks float, by using a removable “skirt” and small propellors for propulsion, as seen in this video clip of an M4 Sherman DD (Donald Duck) Tank.
Rickard, J (24 April 2008), Panzerkampfwagen III als Tauchpanzer , http://www.historyofwar.org/articles/weapons_panzer_III_tauchpanzer.html
Robert Forczyk “Tank Warfare on the Eastern Front 1941-42: Schwerpunkt” Pen & Sword Publishing, 2014.