Why did the Allies win the Battle of the Atlantic?
In the early stages of the Battle of the Atlantic, the German U boats were very effective and sank about 3,000 British ships. This was effective because the Allies had no reliable methods for beating the U-boats until 1941. The Allies learned a lot from the previous years of fighting and so they improved their intelligence, weapons, tactics, aircrafts, radios, and shipbuilding. They also had able-bodied men that would not give up. These improvements helped the Allies win the Battle of the Atlantic by making the U-boat threat their top priority.
So in order to beat the U-boats, the intelligence was improved. The British code breakers at Bletchley Park became better at decoding the German codes. This allowed them to figure out the location of the U-boats so transferring conveys became easier. They would guide conveys away from the U-boat wolf packs and so there would be no interference. This helped the Allies import materials they could not before and these imports helped the civilians and the navies.