Answer:
German Submarines that hunted in "wolf packs"
Explanation:
The Battle of the Atlantic was the longest battle fought during World War II, it began shortly after the war started in 1939 and it lasted until Nazi Germany surrendered in 1945. It was a naval blockade and counter-blockade by the Axis and the Allies.
The worst part of the battle was during the last years of the war, from 1940 up to 1945. British troops needed approximately a million tons of supply per week and as they were on an island all of them must be carried by ship. The German submarines were the ones who caused more damages.
The submarines of the Axis tactic was to hunt the boats in what was called "wolf packs", instead of going one submarine against a boat when one spotted a ship with supplies it contacts by radio with others submarines nearby and they all attacked together at night when they were hard to see by the crew.
I hope this answer helps you.
