December 10, 1941 North Atlantic
That U-boat skipper will be court-martialled when he gets back to France. He just committed the same error as Jaroschek, only worse - engaging the enemy without first making a contact report. It's worse because he's not a lieutenant in his first combat action, he's veteran senior officer, and because
he has explicit orders to make such a report and not engage. The standard U-boat tactic was to post a group of U-boats in a scouting line to detect convoys. They would run surfaced, submerging if an airplane came over (rare at this time) or any Allied ships got near. In the latter case they would rely on hydrophones and periscope to identify and track the Allied ships.
When a U-boat sighted a convoy, it would wait until the convoy was well clear, then surface and radio the convoy's position, course, and speed to U-boat HQ in France. HQ would then issue orders to all U-boats in that group to assemble ahead of the convoy (which they could do because their surfaced speed was much greater than the convoy's. The next night, the entire group of U-boats would attack the convoy simultaneously, running surfaced. (A U-boat's low profile was nearly invisible in darkness, and the cold Atlantic often provided fog and mist.) Such a "wolfpack" attack could overwhelm the convoy's escorts, leading to slaughter of the merchant ships.
This tactic was far more effective than the usual practice of individual submarines loitering around shipping lanes, waiting for targets. However, it was very dependent on sighting reports, and generated lots of radio traffic between U-boats and HQ, fodder for Allied HF/DF.
More importantly, when the Allies were reading U-boat Enigma traffic, they knew where the U-boat scouting lines were and could route convoys around them. ("Playing blind-man's-bluff with their eyes open", in one chronicler's phrase.) The Allies enjoyed this advantage from mid-1941 through January 1942, when losses were much reduced.
In February 1942, the Germans adopted a new Enigma key for U-boats only, which included additional rotor wheels. This new key was finally broken in November 1942 by Alan Turing - but the Allies lost six million tons of ships in the meantime.
In March 1943, the Germans tweaked U-boat Enigma, and it was secure for ten days. During those ten days the Germans savaged several convoys, especially HX229 and SC122, which lost 22 ships. Until Turing re-broke the U-boat key, the Admiralty feared the Battle of the Atlantic was lost.
(Running off at the fingers here, but I hope the information is useful.)