Why did massing U-boats against escorted convoys make the submarines easier to find?
Short answerA single submarine could not inflict enough damage, so wolfpacks depended on radio coordination, and Britain had invested heavily in detecting and analyzing those signals.
NotesA single U-boat could not do enough damage to an escorted convoy, so several boats had to gather before an attack. That concentration created radio traffic which British stations could detect and analyze. Traffic analysis could reveal a threat concentration even without reading the full message content. Wolfpack coordination therefore exposed information that escort forces could use against the submarines.