When submarines were first used more than 100 years ago, hardly anyone believed in their usefulness. Many admirals were convinced that the simple "submersibles" could not stand up to the powerful battleships.
This changed in the First World War. For the first time, submarines operated militarily in larger numbers. The reconnaissance boats quickly become hunters that sink enemy ships.
In British and Allied propaganda, the German submarine became synonymous with treachery, cruelty and inhumanity in naval warfare.
The German submariners were hailed as heroes at home. The image of the U-boat commander as a silent hunter did the rounds. This heroic glorification has little to do with the reality and the danger the crews find themselves in on every mission.
Submarines originated from a completely non-military idea, namely to be able to look at the world under water.
In its history, the submarine was and is both a deadly steel monster and a vital shelter.
As impressive as its construction is, as terrifying is its destructive power. Hardly any other weapon triggers as many emotions as the submarine. It strikes from ambush and can tear the whole world into the abyss with nuclear missiles.
Episode 1 documents the beginnings of submarine development at the end of the 19th century up to the outbreak of the Second World War. Submariners, historians and military experts put the events into context.