What was a U Boat? Why do you think the Germans used them to attack?

U Boat is called Undersea Boat.  The following is the reason why germans used them to attack.

Explanation:

U Boat is the abbreviation of Undersea Boat.It is also called as Unterseeboot.It is called a German submarine.There are many ships during the war. So to sink those many ships germans used the Undersea boat.The Germans sank 5000 ships during the world war.They measured more than 13 million gross register tons during the war.The Germans used them to attack those ships using the Undersea boat.