Radar played a huge role in World War 2. Half of all U-Boat sinkings in World War Two were the result of attacks by Allied aircraft. As the war progressed, radar became more sophisticated, more accurate, and more transportable. As aircraft, especially sub-hunters, were equipped with radar, U-Boats could no longer count on the natural protection that weather could afford. Heavy cloud cover and fog protected the U-Boats at the beginning of the war as they spent the majority of their time patrolling the surface but radar destroyed this protection. As mentioned in this video, German high command would not believe that the allies had these kind of capabilities and regularly attributed these loses to bad luck or ineptitude on behalf of the U-Boat commanders. This video is from a snippet of a show on this little known fact.
Over 80% of men who served in the German U-Bootwaffe perished.
Some say this is a sign of bravery. And it is. But it is also a sign of complete denial on the part of the German Navy High Command to recognize that U-boats at they existed in later years of the war were simply obsolete and thousands of men died for nothing. Even though German surface ships and even aircraft had radar later in the war, Admiral Dönitz refused to believe that the Allies could make an effective radar set small enough to put into a convoy escort ship. Even though his commanders told him over and over that the Allied convoy escorts had radar, he refused to believe it. At one point he asked two of his top commanders if the Allied escorts had radar. They affirmed without hesitation that Allied escort ships had radar. Doenitz threw them out of his office. The two officers were Teddy Suhren and Erich Topp and they both recount the story in their individual memoirs.