<P> From 1955, the West German Bundesmarine was allowed to have a small navy . Initially two sunken Type XXIIIs and a Type XXI were raised and repaired . In the 1960s, the Federal Republic of Germany (West Germany) re-entered the submarine business . Because West Germany was initially restricted to a 450 tonne displacement limit, the Bundesmarine focused on small coastal submarines to protect against the Soviet Union (Russian) threat in the Baltic Sea . The Germans sought to use advanced technologies to offset the small displacement, such as amagnetic steel to protect against naval mines and magnetic anomaly detectors . </P> <P> The initial Type 201 was a failure because of hull cracking; the subsequent Type 205, first commissioned in 1967, was a success, and 12 were built for the German navy . To continue the U-boat tradition, the new boats received the classic U designation starting with the U-1 . </P> <P> With the Danish government's purchase of two Type 205 boats, the West German government realized the potential for the submarine as an export . Three of the improved Type 206 boats were later sold to the Israeli Navy, becoming the Gal - class . The German Type 209 diesel - electric submarine was the most popular export - sales submarine in the world from the late 1960s into the first years of the 21st century . With a larger 1,000--1,500 tonne displacement, the class was very customizable and has seen service with 14 navies with 51 examples being built as of 2006 . </P> <P> Germany has brought the U-boat name into the 21st century with the new Type 212 . The 212 features an air - independent propulsion system using hydrogen fuel cells . This system is safer than previous closed - cycle diesel engines and steam turbines, cheaper than a nuclear reactor and quieter than either . While the Type 212 is also being purchased by Italy, the Type 214 has been designed as the follow - on export model and has been sold to Greece, South Korea and Turkey . </P>

What kind of submarine did germany develop during world war i