The earliest U-boat types fielded by the Kriegsmarine in World War II comprised the Type I and Type II series. These submarines formed the foundation of Germany's submarine fleet at the outbreak of war.
Type I
The Type I U-boat was a class of two ocean-going submarines operated by the Kriegsmarine. They were large, double-hulled boats intended for ocean patrol. U-25 and U-26 were the only two boats of this type built. Both were laid down in 1935 and launched in 1936. The Type I proved to have handling difficulties and was not pursued further, leading to the development of the more successful Type VII and Type IX designs.
Type IIA
The Type IIA was a class of six small coastal submarines. They were single-hulled boats with a displacement of 254 tons surfaced and 303 tons submerged. Armed with three bow torpedo tubes and carrying six torpedoes, they had a range of 1,600 nautical miles at 8 knots on the surface. These boats were primarily used for training and coastal operations in the North Sea and Baltic. U-1, the first of the class, was commissioned 11 days after being launched.
Type IIB
The Type IIB was an improved version of the Type IIA with increased fuel capacity and range. Twenty boats were built (U-7 through U-24, U-120 and U-121). They displaced 279 tons surfaced and 329 tons submerged, with a range of 3,100 nautical miles at 8 knots. The Type IIB served extensively in the early war years in the North Sea and Baltic.
Type IIC
The Type IIC featured further improvements, with eight boats built (U-56 through U-63). They displaced 291 tons surfaced and 341 tons submerged. These boats had an increased diving depth and improved habitability compared to earlier Type II variants.
Type IID
The Type IID was the final and largest variant of the Type II series, with sixteen boats built (U-137 through U-152). They displaced 314 tons surfaced and 364 tons submerged, with additional saddle tanks providing extended range of 5,650 nautical miles at 8 knots. The Type IID boats served primarily in the North Sea, English Channel, and Mediterranean.
Type II Specifications
| Specification | Type IIA | Type IIB | Type IIC | Type IID |
|---|---|---|---|---|
| Displacement (surfaced) | 254 tons | 279 tons | 291 tons | 314 tons |
| Displacement (submerged) | 303 tons | 329 tons | 341 tons | 364 tons |
| Torpedo tubes | 3 bow | 3 bow | 3 bow | 3 bow |
| Torpedoes carried | 5 | 5 | 5 | 5 |
| Crew | 25 | 25 | 25 | 25 |