ON THURSDAY AFTERNOON, WITH U-20 SUBMERGED and headed out to sea, Schwieger made his decision: he resolved to abandon his effort to reach Liverpool, despite his orders. Within the culture of U-boat leadership, this was his prerogative. Out of touch with superiors and friendly vessels, only a commander could know how his patrol was unfolding and what threats or challenges he faced. Still, Schwieger devoted nearly a full page of his War Log to his rationale.
The weather was the biggest factor in his decision. The barometer, and the fog that had dogged his course all day and the previous night, and the strangely calm weather—here he used the lovely German word Windstille—suggested to him that the fog would linger for days. “The poor visibility,” he wrote, “makes it impossible to sight the numerous enemy patrols, trawlers and destroyers, which may be expected in the St. George[’s] Channel and the Irish Sea; therefore we will be in constant danger and compelled to travel submerged.”
He assumed that any troop transports leaving Liverpool would do so at night, with destroyer escorts. The only way to spot these ships was to remain on the surface, he wrote, but doing so in fog and darkness was too dangerous, both because of the risk of being run over and because the destroyers—fast and heavily armed—could not be spotted in time for him to evade attack.
Also, he had only three torpedoes left, of which he wanted to hold two in reserve for his return journey, standard practice for U-boat commanders.
And then there was the fuel problem. If he continued forward to Liverpool, his supply would run so low that he would be unable to return by the same route that had brought him here. He would be forced to take the North Channel, between Scotland and Ireland. While the route had become much safer for British merchant ships, for U-boats it had become increasingly dangerous. The last time he had gone that way he had encountered heavy patrols and unceasing danger. He vowed not do it again “under any circumstances.”
He planned to continue attacking ships, he wrote, but in waters well short of Liverpool, at the entrance to a different passage—the Bristol Channel—through which ships traveled to reach the English port cities of Swansea, Cardiff, and Bristol, “since chances for favorable attacks are better here and enemy defensive measures lesser than in the Irish Sea near Liverpool.” Though he had only one torpedo available for immediate use, apart from his two in reserve, he had plenty of shells. He resolved to continue attacks until two-fifths of his remaining fuel was used up.
But once again he was stymied by the weather. At 6:10 that evening he looked through his periscope and again found only fog, with visibility limited to 30 yards in any direction. He continued out to sea, beyond the heaviest lanes of traffic, to spend the night. He planned to surface the next morning, Friday, to run his diesels and recharge his batteries, in preparation for the day’s hunting.