Panzer III Ausf.G w/5cm Pak After German forces had swept across Western Europe as undisputed champion in 1940, the lone resistance came from the British Isles. It was planned that Germany would conduct an amphibious invasion of Great Britain under the codename Operation Sea Lion, and to this end a number of Panzer IIIs were especially converted into diving tanks. These were known as the Tauchpanzer III, and they had the ability to drive along the seafloor totally submerged thanks to a breathing apparatus. During the planned invasion, they would have been lowered from ships onto the seafloor near the coast and they could then drive onto the shore. In the end these tanks were not used to cross the English Channel as it was decided to bring Britain to its knees via the Luftwaffe instead.