Kusch's first patrol

On 20 March 1943, U-154 left Lorient to set off on its fifth patrol, the first with Kusch in command. Shortly before leaving, Kusch ordered his stoker to remove the picture of Adolf Hitler in the officer's room saying "Take that away, we're not practicing idolatry here". It soon became clear that there were political differences between Kusch and the 1st watch officer Leutnant zur See Ulrich Abel and chief engineer Kurt Druschel, both dedicated Nazis.^[1] Abel and Druschel were later described as "typical officers who believed in victory and always proudly referred to themselves as followers of the Führer."

Kusch made no secret of his anti-Nazi attitude; on the contrary, it was known to the entire crew. Because of the limited space on the submarine, word of Kusch's attitude would have spread quickly. Ensign Kirchammer later testified: "[Kusch] once told us ensigns that we should form our own opinions and not allow ourselves to be influenced by propaganda." Kusch spread a joke among the crew: "What do the German people and a tapeworm have in common? They are both surrounded by brown matter and are doomed."^[1]

During the patrol, U-154 attacked a convoy off Cape São Roque on the Brazilian coast and sank two freighters and a tanker.^[1]

On 3 July 1943, U-126 and U-154 were on their way back to Lorient together when at 02:44 an enemy aircraft appeared and dropped depth charges on the boats. Both U-boats dived immediately to avoid the attack. Since no communication with U-126 was possible after the dive, Kusch assumed that U-126 had continued to dive and was therefore out of range. However U-154 soon heard cracking noises, which indicated the implosion of U-126 due to water pressure. Kusch decided to continue underwater and surfaced 4 nautical miles (7.4 km; 4.6 mi) from the scene of the attack at 07:07 to search for survivors, but broke off the search at 08:33 due to the threat of another attack.^[1]

Although Kusch's behavior during the attack and afterwards was assessed as correct by the flotilla commander, according to Kirchammer, Abel seriously reproached Kusch for not having made intensive rescue attempts for the U-126 crew which included one of Abel's friends. "From that moment on, Abel was literally inflamed with hatred and the previous understanding, which he had observed between the officers at least on a professional and comradely level, despite their completely diametrically opposed political views, was completely destroyed from now on." After the patrol, Abel was judged to be unsuitable for the position of commander. The radio mate Janker considered this to be "the real cause that gave rise to the desire for revenge and revenge in Abel."

Kusch's second patrol

U-154 left Lorient on 2 October 1943. Radio mate Kurt Isensee testified that the political arguments between Kusch and Druschel and Abel became increasingly heated during this patrol:

"As a Sonar operator, I often witnessed political conversations that took place in the officers' lounge, and from which one could clearly see that it was not just about a conversation like on the first trip, but that Druschel and Abel used every opportunity to oppose them. I, too, am firmly convinced that this opposing position arose from offended vanity, which in turn arose from the fact that Lieutenant Abel had to make another trip as a trainee commander."

Isensee said that "apart from two or three scribblers, the entire crew was on the commander's side." He was therefore of the opinion that Kusch's statements would not have been detrimental to the boat's strength. Wehrmacht Medical Officer Hans Nothdurft was also on board this trip to carry out scientific measurements on board a front-line boat under tropical conditions. On 12 June 1946, Nothdurft made an affidavit in front of the CIC Heidelberg, which described living with the officers of U-154. In this document he described Kusch's behavior, but in contrast to Isensee he expressed himself negatively:

"He considered the war criminal and lost, the submarine ridiculous and finished. He foisted this opinion on everyone, though people would not hear it for fear... There were often violent arguments between Abel and Druschel on the one hand and Kusch on the other."

In the course of the second patrol, the officers planned to report Kusch, but according to Nothdurft this was not done at first. He further stated that Abel and Druschel tried to win him over to their side and convince him that Kusch was a coward, a defeatist and anti-Hitler. Abel and Druschel were serious about their plan: they said to Nothdurft: "As a medical officer, you are the senior officer on board. That makes you a splendid leader of our official communication against Kusch. As a member of the army, you are excluded from being able to pursue your own advantages in eliminating Kusch."

Kusch's habit of listening into Allied radio stations was another accusation leveled at him later. According to Nothdurft, Kusch "had the radio officer tune in to hostile stations several times a day." Nothdurft reports that Kusch called Hitler "a madman, a criminal, the worst misfortune that could befall the German people, and a mad carpet-biter." Nothdurft says he saw evidence that Kusch planned to defect and hand the boat over to the enemy. According to Nothdurft, Kusch's political instructions corresponded "without a doubt... occasionally to the request to desert together with the whole boat".^[1]

The patrol was unsuccessful and U-154 returned to Lorient on 21 December 1943.^[1]