The Germans used __________, submarines that would sink any ship that is considered to be in water of a warzone.

The Germans used **U-boats**, submarines that would sink any ship considered to be in the waters of a warzone.

Extra: U-boats, short for "Unterseeboot," which is German for "undersea boat," were military submarines used by Germany, particularly in World Wars I and II. During World War I, U-boats were employed effectively to disrupt supply lines by enforcing a blockade around the United Kingdom, sinking military vessels as well as civilian ships, which they considered to be legitimate targets as part of their unrestricted submarine warfare strategy.

Their use in World War II was also significant. A notable strategy employed by the Germans in WW2 was the "Wolfpack" tactic, where groups of U-boats would hunt together and attack convoys of ships, which were the main method used by the Allies to transport war supplies across the Atlantic Ocean.

The employment of U-boats has had a significant impact on naval warfare, changing the way that navies had to defend against underwater threats. This led to the development of new tactics and technologies for anti-submarine warfare, including the use of sonar for detecting submarines, development of depth charges, and later on, the improvement of convoy systems with better escort vehicles and coordinated defenses.