On May 13, 1917, an utterly ordinary day in the midst of war, marked a fresh beginning for Zhang Hainuo, for on that day, he witnessed the sunrise over the Atlantic Ocean.
Since his journey to this era, whether on the Sedlitz or the U21, Zhang Hainuo had never ventured into the waters of the Atlantic. In contrast to the tranquility of the Mediterranean and the raging storms of the North Sea, this vast ocean presented an entirely different ambiance.
Throughout the previous night, Zhang Hainuo had remained awake, contemplating the British blockade in the northern North Sea. It was their last line of defense to prevent German ships from entering the Atlantic, often referred to by German naval officers as the final threshold to the Sea of Freedom. To guard this vital passage, the British not only stationed their main fleet in the Pentland Firth but also deployed numerous cruisers, destroyers, and airships in the vicinity, with some critical areas even rigged with mines.
Hence, no German U-boat captain dared to be complacent while crossing these waters.
From the early hours of the morning, traversing the area where British ships were most frequently encountered to entering the North Atlantic before dawn, Zhang Hainuo had stood watch on the submarine's conning tower alongside Edwin and Simon. Fortunately, the northern exit of the North Sea was much wider than the English Channel, and the British could not deploy their forces comprehensively across the expansive 200-mile-wide area. Although they encountered two patrolling British warships, they managed to evade them successfully.
Simon, who had participated in three missions in the Atlantic, informed Zhang Hainuo that the threats diminished significantly once they left the North Sea, while the potential prey increased substantially. German submarine captains favored attacking lone merchant ships or armed merchant cruisers, despite the greater difficulty posed by escorted convoys, often consisting of large tonnage vessels or those carrying vital supplies. Moreover, sinking a Canadian or American troop transport ship was equivalent to eliminating at least an entire infantry company on land, a feat worth boasting about!
By late morning, Zhang Hainuo's crew received a telegram from U89, essentially stating that they had safely crossed the British alert line and entered the waters of the Atlantic, wishing the others a pleasant "hunt."
After the harrowing battle they had just experienced, Zhang Hainuo no longer harbored as much disdain for the captain of U89, the conservative gentleman. Perhaps his initial decision was made from his own perspective, as Von Laurenz had suggested, everyone had their own duties.
Zhang Hainuo courteously replied to the telegram, informing them that their submarine had also safely crossed the British alert line and advising them to beware of the formidable British underwater detection devices and depth charges.
Exiting the northern North Sea did not mean an immediate entry into the Atlantic "hunting ground." According to the confidential instructions received from the submarine command before departure, Zhang Hainuo and his U171 were deployed to the areas northwest of Scotland, 200 to 300 miles, and southwest of Iceland, 150 to 250 miles. These regions were part of the Liverpool-North America shipping route, but the command also warned that the British, along with the recently joined Americans, had bolstered escort forces along this route. As the commander of U171, Zhang Hainuo had the authority to decide whether to launch an attack upon discovering British or American merchant ships or convoys in these waters.
A few centimeters on the nautical chart often represented long distances, and it was not until noon on May 14th that Zhang Hainuo and his U171 arrived at the designated operational area.
Life as a sea hunter sounded exhilarating, but in reality, it was mostly mundane, with long hours of waiting testing one's patience. Furthermore, the inherent disadvantage of submarines in terms of visibility compelled submarine captains to maneuver their vessels near the shipping lanes to expand their observation range.
The waves near the North Atlantic, close to Iceland, were not as fierce as those in the northern North Sea but were significantly stronger than those in the Mediterranean. Moreover, the temperatures were lower here, even in late spring, with sea surface temperatures remaining below 10 degrees Celsius.
Zhang Hainuo's first encounter with a potential target occurred at 9:22 p.m. on May 14th. It was an unidentified merchant ship sailing under blackout conditions. If it were before Germany's unrestricted submarine warfare order, Zhang Hainuo would have to confirm the vessel's identity before taking action. However, since February 4, 1917, "German submarines may attack without warning any merchant ship destined for British waters."
Unfortunately, this merchant ship seemed akin to a fleeing rabbit, refusing to provide U171 with an opportunity to position for an attack and swiftly disappearing into the night.
Six hours later, at dawn on the second day, U171 spotted a vessel traveling from east to west. While not particularly fast, its course remained stable. Zhang Hainuo attempted to position for a torpedo launch twice but failed. Considering the high likelihood of a failed torpedo launch and the possibility that it was a British Q-ship, a disguised anti-submarine vessel, Zhang Hainuo refrained from initiating an attack and watched as the vessel sailed away.
The fourth day brought ships with stable speeds and courses into Zhang Hainuo's view, not just one but several. However, they were surrounded by a group of cruisers and destroyers, resembling a formidable entourage, deterring any thoughts of engaging them. While Edwin and Simon advised against provoking the convoy escorted by warships, Zhang Hainuo had other ideas.
"Send a coded message to headquarters. We have spotted a large British convoy in the 52nd area, comprising approximately 15 to 20 merchant ships escorted by 8 to 10 warships. Request immediate deployment of nearby submarines to support us!"
After issuing these orders, Zhang Hainuo quickly calculated the positions, speeds, and U171's location.
"Maintain one-third speed ahead. Alter course to 350 degrees. Prepare for submersion!"
Edwin and Simon exchanged glances but said nothing, diligently carrying out the commands.