As the sun rises above the sea level, a new day begins, and the entire Mediterranean Sea is bathed in golden sunlight.

The Libyan port of Tobruk, the most important military base of the Afrika Korps in North Africa, is gradually becoming lively, with not only a strong fortress, a well-established aviation base, but also a port with relatively good facilities. More important is its location, which is neither as far as Benghazi nor as close to Port Matrouh as Benghazi, but is a very advantageous point of support. Transporting supplies from Benghazi to El Alamein by truck, losses on the way, consumption back and forth, etc., accumulate and it would be nice to have half a ton of gasoline left on the front line for every ton of gasoline delivered. And the port of Matrum is too close to the front line, British planes come to bomb almost every day, sometimes even twice a day, the port facilities are repaired and bombed, and after the bombing is completed, there is hardly a time when it is intact. Although Tobruk was also patronized by British bombers from Malta or Cairo respectively, because they happened to be in the middle of two enemy bases, the number of bombers who came to patronize was relatively limited, and the time spent in the air was not too long, and the fighter wing of the 8th Air Force stationed in the air provided effective defense, and the overall safety was still guaranteed.

The main reason for the port's busyness is to process fuel that arrived three days ago, most of which goes through a variety of pipelines into combat-ready tanks. In preparation for bombing, the Afrika Korps took Tobruk from the British and spent a lot of effort repairing the oil storage facilities, placing almost all the tanks underground. The other part of the fuel is drummed and sent to the front by truck, which is the blood that sustains the war.

The errand of transporting supplies to North African ports had long been regarded by the Italians as a daunting task, and they could delay and escape, but this time not only did Prime Minister Mussolini personally issue a sternly worded order, but the German garrison was directly dispatched by the gendarmerie on the orders of Field Marshal Kesselring. Although the military has repeatedly said that the route is very safe, and the air force will provide full escort, the captains are all elite figures, and they have heard too much news that the freighter was sunk by the British in the past six months, so they naturally will not take this cheap guarantee to heart, and a pair of ears simply filter this kind of words directly, just trembling and setting off on time. Less than half a day after leaving the port, the captain beckoned the crew to prepare life-saving equipment and dinghy in order to buy the fastest time for escape. Unexpectedly, all the precautionary measures were useless in the end, and the two Italian oil tankers successfully docked at night, and the cargo was unloaded in less than a day, and the whole process was completed in one go and without any obstacles. Until the evening when they left the port, the two captains of the tanker were still in a stunned stage, saying that they had never encountered such a smooth replenishment process, and that during the two-day and three-night voyage, it was as if the British warships, submarines, and planes had deliberately avoided them, and there were no British planes to disturb them even when they were operating in the port, which made people involuntarily have the illusion that they were still in peaceful years.

When Guderian received the telegram from Tobruk, a satisfied smile appeared on the corner of his mouth, and the purchase of 6,000 tons of fuel oil means that the next stage of the Afrika Army's combat plan has the most solid foundation. None of them expected this clever counter-exploitation of the British army's unfavorable grasp of their own ciphers, and Guderian used the typical trick to ensure the safety of the transport by misrepresenting the time of supplies to the British—the two ships would not arrive until the afternoon of September 6 on the British calendar, and the rigid British, so convinced of their own information, had not bothered to make a futile trip to Tobruk for the first two days.

At this time, less than 60 nautical miles outside the harbor, two dark and shiny periscopes rose in unison, vigilantly observing the surroundings, and only after finding that everything was normal, did they re-land contentedly. Soon after, two iron-gray slim bodies emerged from beneath the sea level. These are two T-class submarines belonging to the Second Submarine Detachment of the Royal Navy, with a displacement of 1090/1571 tons (underwater), as follow-on submarines designed to replace the O-class, P-class and R-class boats, the T-class submarines were built under the restrictions of the London Naval Treaty, and compared to the S-class boats, it has increased tonnage, more torpedoes and more fuel, and is relatively more reasonable in design. The seven submarines of the Second Submarine Detachment were all T-class, and after the start of the war, they were incorporated into the Mediterranean Fleet.

To deal with two Italian tankers, the command of the Mediterranean Fleet ordered the 2nd Submarine Detachment, stationed at the Malta base, to send competent forces to complete the task. The 2nd Submarine Detachment carefully studied the combat mission and dispatched two submarines, the Turbulent (Royal Navy N98) and the Traveller (Royal Navy N48), to ambush outside the port of Tobruk, and the combat order clearly stated that the enemy ship was to be completely sunk and to be completed before it entered the port to unload. To ensure success, the detachment selected an Italian tanker target for each submarine and stipulated that the overall operation would be commanded by the high-ranking captain of the Furious, Rear Admiral John Wallace Linton.

The telegram informed the Italians that the time of their appearance was on the afternoon of 6 September, and although it was the habit of the Italians to be late rather than early, for the sake of safety and navigation, the Furious and the Voyager departed from their base in Malta ahead of schedule, and went out day and night all the way, and after arriving at the designated position in the early morning of 6 September, they went into hiding.

In the opinion of the captain of the Voyager, Captain Michael Beauchamp St. John, the order given by the fleet command was carefully considered, and although the submarine usually uses the means of ambush on the way, because it does not know the clear route of the Italians, this tactic is likely to pass by the target, but the ambush outside the port is different, unless the Italians do not come to Tobruk, it must not escape. He remembered the solemnity on the face of the commander of the detachment before the departure when he conveyed the order of Vice Admiral Henry Harwood, commander of the Mediterranean Navy: "The Mediterranean Fleet has the important responsibility of ensuring the logistics of the Eighth Army, and they are now engaged in a fierce battle with Guderian's African Army, and it is very important to us that the enemy must not be allowed to get fuel supplies from above. He secretly made up his mind that he must send the two tankers to the bottom of the sea.

As an important port in North Africa, Tobruk used to be regarded as a hub of intensive shipping, but since the beginning of the Great War, especially after the repeated attacks of the Italian transport fleet, the entire route is now empty, and after searching for a long time, not a single ship can be seen, and Major Linton is very satisfied with this, because it means that the difficulty of searching for ships is greatly reduced. He is very confident in the ambush of oil tankers, this kind of task they have carried out many times in the past six months or so, since the black house in Britain used the Turing machine to decipher the German code, all the secrets of the military operations of the German and Italian troops in North Africa have been seen at a glance, the ridiculous Germans have always thought that the Italians are unreliable and betrayed them, on the contrary, although the Italians are not very reliable in many things, their code is still relatively useful, at least until now it has not been cracked. Of course, it was not interesting to crack the code of the Italians, after a series of naval battles such as the night attack on Taranto, the Battle of Cape Matapan, and the Battle of Malta, the Italian naval fleet, which had lost troops and was short of fuel, was basically cowering in the base port and refused to come out.

From early morning to morning, from morning to noon, until the sun set in the afternoon, there was no trace of the Italian oil tanker, and the two submarines finally lost their breath. At first, they were able to stick to the plan of lurking underwater, sticking out their periscopes at intervals of one hour to observe, but the more they got to the back, the more anxious they became, and before the sky was completely dark, they resurfaced to recharge their batteries. Major Linton, who was more experienced and knowledgeable about the tempers of the Italians, sent a telegram to the Voyager, asking them not to be discouraged, especially after nightfall. Under the pacification of the two commanders, the restless military spirit of the crew gradually calmed down, and they persisted in the darkness for a whole night, constantly observing the sea situation and preventing the Italian oil tankers from slipping into the port at night, but still to no avail.

The sun rose again the next day, but this time the two submarines did not dive quickly. After being suffocated underwater for so long, not seeing the sun for several days, coupled with the foul air in the cabin, the ubiquitous engine noise, and the sultry heat caused by the Mediterranean climate, the lads could hardly hold back, the two commanders discussed it by telegram, and decided to seize the time to breathe and let the wind out, and raise the morale of the crew.

As the captain gave the order, the lads cheered and climbed out of the hatch and gulped in the fresh air, the sailors at first walked around the bow of the ship in twos and threes, and then simply gathered in a circle to brag and chat, but Captain Braukamp faithfully performed his duty, constantly looking into the distance through the high-powered telescopes on the deck, he could see the Libyan fishermen fishing near the port, but there was no trace of the Italian tankers, and he was sure that it was impossible for such two large tankers to slip out from under his nose.

Where did the Italian ship go?