What's some info i should know about the U-boats used in World war 1 and 2?

This is for a project|||U-boats were responsible for the only direct attack on North America by German forces in World War 2, when U-518 hit a loading pier in Newfoundland with a torpedo.





U-boats generally used battery powered electric engines when submerged, and diesel engines on the surface. The diesel engines charged the batteries for the electric engines.





Germany's use of unrestricted U-boat warfare, resulting in the deaths of American civilians on passenger ships attacked without warning, caused America's eventual entry into World War 1.





The introduction of convoy systems was an important defence against U-boat attacks on merchant ships, so that the ships could travel in groups escorted by warships. Convoys were used in both wars. In World War 2, the U-boats responded by adopting "Wolf Pack" techniques where they would also operate in large groups by all converging on one convoy.





In World War 2, radar eventually became an important means for aircraft and ships to detect U-boats on the surface from long range.





Many of sinkings of U-boats in World War 2 were a result of the Allies having broken the German Enigma codes by using early computers in a massive code-breaking effort consisting of thousands of staff at Bletchley Park in England. The code-breaking work was made easier when an intact Enigma machine was recovered when the British captured U-110.





U-570 was the only U-boat to fight on both sides in World War 2, after being captured by the British and renamed HMS Graph. The story of her capture is a bizarre tale. The submarine resurfaced after a depth charge attack because the inexperienced crew didn't know that it was safe to dive, and then surrendered to British aircraft.





One of the aircraft then flew in circles round the U-boat for 13 hours, which is how long it took British ships to reach it. The aircraft had been under orders to sink the U-boat, after warning the crew to abandon ship, if no ship arrived by sunset.





The ships were not yet ready to board the surrendered U-boat, so the U-boat crew had to stay on board overnight. They didn't attempt to scuttle (sink) the U-boat to prevent its capture, because the British ships had told them that if they did so then they would not be rescued from the water, resulting in certain death.





At dawn, the Germans repeatedly requested to be taken off the U-boat, which was in a dreadful condition and very smelly, and the British repeatedly refused because they suspected the Germans would let the U-boat sink as they left it.





Another British aircraft, flown by Norwegians, which did not know the U-boat had surrendered, then arrived and attacked it, and even also attacked one of the British ships, which fired back.





Later, losing patience with unsuccessful attempts to take the submarine in tow, the British tried to fire warning shots with a machine gun, but accidentally hit some of the German sailors on the U-boat.





Finally British sailors managed to board the U-boat, and it was towed back to Britain with a constant patrol of British aircraft circling over it the whole way.





The British officer who inspected the U-boat described it:


"The interior of the submarine was unlit and was in a chaotic state; leaks of oil and water from the broken gauge glasses of internal tanks had combined with vast quantities of provisions, flour, dried peas and beans, soft fruit, clothes, bedding, and the remains of scores of loaves of black bread to form a revolting morass that in places was knee-deep. It was subsequently discovered that in this ship the crew's W.C. had been converted into a food locker and overturned buckets of excrement added to the general noisome conditions."|||They were primative subs which stank to high heaven. Apart from the diesel burning engines, the sewage system didn't always work right.|||That serving in a U-boat was the most dangerous armed service, ever. In wwii, of the 39,000 who served, 30,000 were lost.