Due to the stubborn resistance, strong combat effectiveness, and highly targeted tactics of the German army, the US military did not basically wipe out the German troops defending the island until 20 days later, and the sporadic attacks of the remnants of the enemy persisted for more than one month before they completely stopped. The elite 1st Marine Division suffered no less than 12,000 casualties (including more than 2,000 killed and missing), and if it were not for the timely reinforcements sent by the United States, the supposedly undefeated 1st Marine Division would have really planted a big heel in Iceland.

In addition, in the course of the ground attack, 23 US carrier-based planes were also shot down by the Germans, adding to the injuries of the US Navy, which was already suffering a great deal of vitality. However, the losses were greater than the American fleet, and because the occupation of Iceland took too long, a large number of German naval submarines came to the nearby waters and launched attacks on American ships again and again.

If it is an old-fashioned ship-type submarine, it is relatively easy to deal with, after all, the underwater speed is too slow, and if you want to attack, you must first approach the US fleet through surface navigation and then dive to prepare for the attack, so it is easy to be discovered by the US carrier-based aircraft and be attacked, you must know that although the US carrier-based aircraft suffered heavy losses in the previous battles, they were reinforced within a few days (the Atlantic islands that the United States had blackmailed Britain to obtain became the relay point for aircraft transfers) and regained their strength, At least it is enough to deal with submarines, although fleet aircraft carriers are generally not used for anti-submarine purposes, but that is only because the cost is too high, and the cost of losses is too heavy, but this does not mean that the anti-submarine capabilities of fleet aircraft carriers are not strong

However, almost ten days after the first submarine attack on American ships. Some of the German teardrop-shaped submarines also arrived on the battlefield, and the American fleet was in big trouble. The teardrop-shaped submarine can sail continuously underwater for 500 to 600 kilometers, and the new sonar can be installed to find and target the target without sticking out the periscope to launch an attack (Note 1), so it is difficult for the US military to give early warning, and the extremely inconspicuous trajectory of oxygen torpedoes (the stock is not used up so quickly) and hydrogen peroxide torpedoes make US ships even more defenseless.

At the same time, because the drop-shaped submarine has an extremely fast underwater speed, it can quickly withdraw after the torpedo is fired, and the detection range of the US sonar is quite limited, so even if the US military sends a large number of planes and destroyers, it will be difficult to find out it. Most of the time, they can only be beaten in vain. Occasionally, the U.S. military crashes into a big accident or the German submarine makes a mistake, and only then will a teardrop-shaped submarine be found by the U.S. military, and even in that case, the submarine still has some ways to hide from the world. It doesn't have to be impossible to escape

As a result, after being sunk by German submarines 1 heavy cruiser, 2 light cruisers, 19 destroyers, 11 transport ships, 5 landing ships, 2 minesweepers, 1 battleship, 2 battleships, and 1 heavy cruiser. The U.S. fleet only managed to sink 11 old German submarines and force land one. However, none of the eight teardrop-shaped submarines were lost, and if the torpedoes were not exhausted, the US fleet, which was helpless for a while, did not know how many ships it would lose

Fortunately, the U.S. military made a forced landing of the first German submarine during this campaign, and learned about the existence and basic characteristics of the teardrop-shaped submarine. The U.S. Navy finally came up with some ways to limit its role, although due to the limitations of science and technology, it is impossible to completely eliminate the threat of teardrop-shaped submarines as the "wolf pack tactics" of German submarines in history

In fact, in this submarine warfare, the drop-shaped submarines have exposed some weaknesses, first of all, because the underwater navigation is completely powered by the battery pack, so even the drop-shaped submarines mainly adopt the way of floating and sailing on the surface when sailing over long distances, and their water speed is much slower than that of the old submarines, so although their performance in fighting with enemy combat ships is far stronger than that of the old submarines, because of the slow speed of long-distance navigation, it is much more troublesome to mobilize across sea areas.

Because of this, the German 8 teardrop-shaped submarines not only arrived on the battlefield many days later than the old submarines (of course, this is also related to the position of the sea area where they were when they received the order), but also took more time to return after the torpedo was exhausted and return to Iceland, so that it missed the opportunity to damage the American fleet again, because at that time the airfield in Iceland had been repaired by the American army, and hundreds of American aircraft were stationed in Iceland, so there was no need to leave the huge fleet here. Therefore, the drop-shaped submarines that have returned to the battlefield can only be used to spill gas on the transport ships of the US military and the merchant ships of the allies

In the process of breaking the engagement, the teardrop-shaped submarine exposed the second weakness, that is, the cost-effectiveness ratio is low, because the cost of a drop-shaped submarine is worth several old submarines, and the training of the crew also requires more time, so when dealing with relatively low-value targets such as merchant ships, their cost-effectiveness ratio is not as good as those low-cost and faster formation of combat effectiveness. In fact, what really made the drop-shaped submarine completely eliminate the old ship-type submarines was the rapidly improving anti-submarine capability of the US-British allies, and the more powerful the enemy's anti-submarine capability, the more obvious the advantages of the drop-shaped submarine over the ship-type submarine

In any case, the main force of the US Atlantic Fleet, which had already suffered heavy losses, was again sunk nearly 20 combat ships, which was undoubtedly another heavy blow, but because Germany had already lost the sea supremacy that it had so hard to gain, Britain could calmly send a large number of auxiliary ships to support the US forces and help them finally complete the task of occupying Iceland. Due to the lack of capital ships in the German Navy, even after the existing few are repaired, they are not able to recapture Iceland, and the battleships of the United States and Britain in the Atlantic alone are enough to easily suppress them, so once Iceland is taken, there is no need to worry about security at all

With Iceland as an important base, the US military will be like an "unsinkable aircraft carrier," and after that, it will be able to control that vast sea area by relying only on land-based aircraft, and will no longer need the help of aircraft carriers, so that the US Navy can devote only half of its remaining carrier-based aviation units to the Pacific theater. Not to mention that after Iceland was taken away from Germany, the United States no longer had to worry about the direct threat of Germany on its homeland, and at the same time, it was more convenient to assist Britain and strengthen their determination to resist the war to the end

Note 1: Sticking out the periscope can easily expose the position of the submarine, not to mention during the day, even at night, the enemy's airborne radar can also detect the periscope, although because the target is small, the effective detection range is not far, but after all, it is a major threat that cannot be ignored. (To be continued......)