EXAMPLES FROM THE WEB FOR U-BOATS
It was the belief that the destroyer had sunk one of the U-boats.
My own notion of it is that the U-boats have many of us bluffed.
It was all interesting—the life in Paris—but it had nothing to do with U-boats.
Also he urged the crew to have a special watch out for U-boats.
By this time the lurking U-boats had been dealt with in a most effective way.
Early in the war the U-boats were faster than the E's by quite two knots.
All the waters along the coast are infested with the German U-boats.
This was why the U-boats had found it so useful as a rendezvous lately.
There is a crew of only twenty men, because they need them for the U-boats.
Then it was discovered that German U-boats were doing this work.
1916 (said to have been in use from 1913), partial translation of German U-Boot, short for Unterseeboot, literally "undersea boat."