At 50 a.m., minutes after Tan Renhao and Hao Dongjue received the reconnaisance plane's return at the same time, the action order was sent to the "Liqiu." It's just that the commandos can't be dispatched immediately, and the operation can only be carried out around dawn, and it's too early. Lieutenant Colonel Guan Chunsheng asked the communications staff officer to connect to the reconnaissance plane's communication channel, so that the officers on the battleship, including Pan Zekang, who had been left behind by the dead face, could learn about what was happening on the side of the US transport fleet through the report sent back by the reconnaissance plane.

As many as five German submarines entered first, and these five submarines entered from the northwest and southwest directions, respectively, on the two flanks of the convoy route. This is a very typical "wolf pack" tactic, judging from the first time to invest five submarines to attract American escort warships, the German submarine commander must have been well aware of the size of the transport fleet, and also the size of the escort fleet. In addition, the number of German submarines participating in the operation was definitely more than 20 units. According to the minimum matching limit, when a submarine is dispatched to attract escort warships, at least three submarines will be hidden and ambushed on the periphery, and sometimes as many as eight submarines will attack. That is, the number of submarines put into service by the Germans this time is likely to exceed 30!

These five submarines were discovered by reconnaissance planes in the sky when they were still 50 nautical miles away from the US convoy. Because the German submarine was not equipped with a radar, the reconnaissance aircraft overhead was not detected. In addition, all German submarines in the nearby waters took part in the encirclement and suppression of the transport convoy, so that no submarines were found on the periphery waiting for the First Fleet. Thus did not expect that the First Fleet would catch up so quickly. In addition, the reconnaissance planes did not get too close to the US transport fleet, and the radars on the US destroyers did not detect those reconnaissance planes, so they did not know that in addition to the German submarines, the First Fleet was also nearby, and the threat of the First Fleet was certainly much greater than that of the German submarines.

The five submarines acting as decoys were all on the surface and approaching the U.S. military at a speed of 20 knots, while the U.S. convoy had been sailing westward. The speed is about 12 knots. The relative velocity of the two sides is about 28 knots. By about 0:00 a.m., the actual distance between the two sides was less than 20 nautical miles and 0:30 a.m., and the two destroyers in front of the convoy were the first to spot the approaching two submarines and immediately sounded the anti-submarine alarm. At this time, the five submarines that surrounded the first were about 15 nautical miles from the transport convoy, and the nearest destroyer was only 810 nautical miles. The lookout on the submarine had already seen the ground lights on the destroyer's mast. However, these submarines did not dive immediately, but continued to move forward. At 0:45, about 8 miles from the convoy, that is, when the American destroyers were about to arrive, the five submarines quickly dived, then fired a salvo of all the torpedoes in the direction of the bow, and then began to evade the destroyers' attack.

The real threat of this round of torpedo attacks was not very great. At that time, Germany did not manufacture heavy oxygen torpedoes, and although German torpedo manufacturing companies had been working hard to develop electric torpedoes, the results were not significant, and its submarine forces still used old torpedoes that improved reliability. The maximum range of this torpedo is only about 5 miles at most. In addition, the submarine was exposed when it fired the torpedo. The lookout on the destroyer quickly spotted the torpedo trail and immediately raised the torpedo attack. Transport ships, as well as inner escort warships, had plenty of time to avoid the incoming torpedoes. But the task of these five submarines was not to sink the transport ships, but to attract the escort warships. This goal was quickly achieved, and when the American destroyers found twenty mine tracks and determined that five submarines had appeared, eight other escort warships broke away from the formation and followed the torpedo trail to find the German submarines.

Both submarines were initially spotted and were flanked by two escort warships. At this time, the US Navy's ground escort tactics were quite mature. When the U.S. military entered the war, the British Navy summed up a lot of escort experience through bloody lessons, and then the U.S. Navy also paid a heavy price in the Atlantic. The quality of the officers and men of its escort force has been rapidly improved. In the original escort tactics, it was generally a destroyer against a submarine. However, the US officers and men soon discovered that in a one-on-one battle, the destroyer succeeded in killing the submarine less than half.

There are a number of factors that contribute to the reduction of the combat effectiveness of destroyers. For example, before the Great War, many people knew that sonar was an indispensable equipment for dealing with submarines, but few people knew the limitations of sonar in use, and even fewer people knew about the "variable temperature layer". In other words, when the sonar propagates in the seawater, there will actually be a certain angle deviation, and this deviation will lead to the inability to accurately detect the position of the submarine. In the beginning, it was common to drop four depth charges at the same time for an attack, but soon the British began to drop ten depth charges at the same time, and sometimes the commander of the destroyer would even order more than 20 depth charges to be dropped at the same time to counteract the effects of sonar deviations. In fact, however, most of the time, experienced submarine commanders could still take advantage of this to avoid destroyer attacks, and the survival rate of German submarines when attacked by destroyers was even more than 60%.

There are only two real solutions to this problem, one is to drop depth charges in the direction of the bow of the ship, since the sonar deviates little or no when detecting forward. Another option is for the two destroyers to work together, with one destroyer using forward sonar detection and the other destroyer dropping depth charges. What really gave the destroyer the ability to attack the submarine in front of it was the "hedgehog bullet". Initially, the U.S. Navy developed 24 "hedgehog shells", each launcher is divided into six groups, each group of four, each bomb weighs only a few kilograms, and when launched, the trajectory of each "hedgehog bullet" is different, so that when a salvo of 24 "spikes + waiting, it can cover a considerable amount of water. But the "hedgehog bomb" did not really solve the problem, and the tactic of using two destroyers to deal with one submarine was retained.

The coordination tactics of the two destroyers are quite simple, under normal circumstances, the destroyer behind is responsible for detecting the submarine and attacking with "hedgehog shells", if the submarine can be sunk, it is naturally better, even if it does not, it can force the submarine to maneuver quickly, thus exposing the position. And the real main force was the destroyer in front, which used the information provided by friendly ships to drop heavy depth charges. In actual combat, this tactic is used against submarines

The power can reach about eighty. That is, if the submarine's boat I experience, and the luck is not very good, then it will definitely be finished!

The fate of the two submarines that were attacked first was indeed the case, but no anti-submarine battle could be quickly resolved, and this is a major feature of anti-submarine warfare; often, the two sides confronted each other for several hours, and sometimes the destroyer even fought with the submarine for a day or two. The two submarines held out for more than three hours, and the significance of these three hours was very significant.

The fate of the other three submarines on the "decoy" mission was different, all three were XXI-class submarines, and after firing the torpedo, all three submarines quickly turned and got out of the dangerous sea area at maximum diving speed. The XXI-class submarines are close in performance to the Empire's C-class submarines, and the Imperial Navy's submarine forces have proven many times in the Pacific Ocean that their fast diving capabilities are the main bargaining chip for escape. At the same time, the US destroyers dealing with these three submarines were not able to arrive immediately, and as a result, when the US destroyers finally rushed over, the three submarines fled more than a dozen nautical miles away, leaving the destroyers' "must-kill" range long ago, and successfully escaping with their lives.

In fact, the task of the first five submarines was "self-sacrifice". There was an unwritten rule in the German Navy that whoever was the first to spot the convoy would act as a "decoy". In the past few years of sea-breaking operations, the survival probability of the "decoy" is less than 20%, which is several times lower than that of other submarines. Therefore. All the submarine captains on the "decoy" mission knew that they would be sunk for sure, and that if they were able to escape, God would have blessed them, so if they had carried out the mission, they would have known that they would be doomed.

After dispatching twelve battleships to deal with the German submarines, only ten escort ships remained in the formation. And it is almost impossible for these escort warships to completely deal with the surging other submarines. By half past one o'clock in the morning, that is, when a huge hole appeared in the anti-submarine network of the US transport fleet, more than 20 submarines with the main attack mission had arrived at the attack positions one after another. These submarines approach their targets at low speeds from under the surface, and their mission is to get close to the convoy of transports, launch torpedoes, and sink them. Then avoid the American destroyers, retreat to the perimeter to reload the torpedoes, choose a new attack position, and attack again until all the transports are sunk, or the destroyers are sunk, and the battle is over.

Most submarines are launched at a distance of 23 nautical miles from the convoy: they attack from the flanks of the convoy's route, so as to maximize the width of the attack surface and allow the torpedoes to hit the convoy as much as possible. A few daring captains also allowed their submarines to reach the convoy's fairway. It was not until the convoy of transports passed overhead that all the torpedoes at the head and tail were fired at the same time in order to maximize the impact of the attack.

At the same time as the German submarines launched a frenzied attack. The U.S. military escort warships also launched a decisive counterattack. Many escort warships did not find their targets at all, but blindly dropped depth charges. Hopefully, this will scare away the demons beneath the surface of the sea. Only a few destroyers acted more steadily. In the confusion, many German submarines could not accurately judge the situation on the nearby sea surface in the continuous explosions, while the sonar on the destroyer was able to detect the submarine below the surface. Experienced destroyer captains also know how to follow the torpedo trail to look for submarines. Therefore, the battle is not one-sided, after all, destroyers are the nemesis of submarines.

As transport ships exploded and caught fire, the battlefield quickly became chaotic. By 3 a.m., at least six submarines had been sunk by the destroyer. And the number of transport ships hit by torpedoes reached fourteen, seven of which were sunk. The other seven were struggling to sink slowly on the surface. At this time, the fourth batch of "reconnaissance eagles" had already reached the vicinity of the US convoy. Although the situation on the sea was chaotic, this did not interfere with the radar on the reconnaissance aircraft. After more and more transport ships were hit, the reconnaissance aircraft soon detected that there were four escort warships covering a transport ship at all times, and that this transport ship was located in the innermost part of the formation, and it was also the most difficult to attack.

This information was immediately sent back, and at the same time it was received by the "Liqiu", which was obviously the ship that the commando team had to occupy. Guan Chunsheng also immediately called the commander of the assault team and adjusted the arrangements for the assault operation. Because 26 commandos have been prepared, and now 14 transport ships have lost their preemptive value, there are many commandos that are no longer available. After adjusting the assault plan, five commandos were tasked with attacking the extra-protected merchant ship, and as long as one commando team managed to board the ship, it was likely to be successful. But the problem is that there are four escort warships in the vicinity of this merchant ship, and if these four escort warships are not diverted, then none of the assault teams will be able to get on board safely.

By half-past three, when the assault team was ready to set off, the situation took a significant turn. The German submarine, which had completed the first round of attacks and successfully withdrawn and reloaded the torpedoes, did not leave and returned to the battlefield, and the German submarines also discovered the extra-protected merchant ship, and at least three submarines launched an attack on the merchant ship, as a result, two of the four warships guarding the merchant ship were torpedoed, and the other two were forced to leave their original positions. The merchant ship miraculously dodged all the torpedoes and quickly got into the other merchant ships. In this way, it was difficult for the German submarine to keep up with the transfer speed of the merchant ship under the surface, but the reconnaissance plane in the sky was able to continue to track the merchant ship with radar and send the news back to the cruiser "Liqiu" in time, and the cruiser was responsible for guiding the assault team.

Pan Zekang's assault team left the cruiser "Liqiu" at 3:40 a.m., and the battle ahead was still raging. German submarines would not retreat before dawn, and American escort warships would not easily abandon their protected ships. At this point, no one knew if the merchant ship named "Lady Liberty" would sink before the assault team arrived, and even Pan Zekang was not sure, but they had to venture forward, and if they didn't go, then there was no certainty!