During World War II, in order for european allies to continue to exert their combat effectiveness, the United States and Canada needed to continue to transport people and supplies, and the Atlantic Ocean was the only way out. The Allies adopted a strategy of sending a fleet of merchant ships escorted by warships and aircraft across the Atlantic. However, moving about forty merchant ships as a tightly knit unit was not an easy task, and it was even more difficult to avoid being spotted by the cunning Germans. The center of the Atlantic Ocean was beyond the cover of the Allied air forces. This area is known as the "Dark Trench" and is also the area most vulnerable to enemy attacks. On the other hand, in order to cut off the Allied supply lines, the Germans adopted the wolf pack tactics of U-boats. They infiltrated the Atlantic to attack the Allied fleet.
The film tells the story of Tom Hanks' command across the treacherous North Atlantic, while also dealing with the German U-boat wolf pack and successfully escorting the merchant ships.
The screenplay for the film Greyhound is based on Follies' World War II naval battle novel Shepherd. The author of this original novel claims to be a non-fiction novel inspired by real events. Moreover, the author consulted a large number of historical materials, the information is quite solid, especially the protagonist's in-depth description of the combat command of a large number of details, so that for a long time, the book was used as a textbook of the United States Naval Academy, let's talk about it.
After the outbreak of the European War in September 1939, the battle for control of the Atlantic between Germany and Britain and France began. At the time, the Atlantic Ocean collected three-quarters of the world's shipping. It was vital to Britain, known as the Maritime Colonial Empire. It is the "lifeline" of British imports of strategic materials, industrial raw materials and grain, accounting for more than 80% of British food and strategic materials. Relying on overseas imports, an average of 2500 ships sail at sea every day.
At the beginning of the war, the German Navy had only 3 pocket battleships and 57 submarines, and only 2 pocket battleships and 23 submarines could travel to the Atlantic at any time. But relying on such a weak force, on September 3, 1939, the first day of Britain's official declaration of war on Germany, the U-30 submarine sent by Dönitz successfully launched the first battle, sinking the British cruise ship Athena, kicking off the prelude to submarine warfare and anti-submarine warfare in World War II.
Since its strength could not compete head-on with British surface ships, Germany tried to force Britain to surrender by attacking Atlantic shipping. Therefore, the Atlantic naval battle, which was dominated by attacks and counterattacks on sea lines of communication, became its main form and characteristic. During World War II, German Admiral Dönitz changed the tactics of submarines fighting alone, organizing multiple submarines into small groups and taking turns against enemy ships and means of transport like wolves, so he was called "wolf's head". Wolf pack tactics are about pooling weak forces to jointly destroy large fleets. During the operation, one or more ships are dispatched to conduct reconnaissance at sea. Whenever a submarine spots an enemy ship, it will signal all submarines that are closer and launch a surprise attack on the enemy at night. The usual practice is that when a target is spotted, each ship passes through the gaps or flanks of the opposing escort fleet, avoiding its fire strike barrier and approaching the target. During the day, ships take advantage of the attack in all directions and hide underwater. At night, they suddenly surface and attack the target at the same time. "Wolf Pack Tactics" got its name from this.
In the North Atlantic, far from Britain and the United States, fleets carry supplies across the Atlantic. On the way, the most vulnerable place is the atlantic center, which is beyond the range of air force escorts. The same is true of the situation described in the film, because the Allies did not deploy escort aircraft carriers in 1942, so there was indeed a certain distance on the route without the protection of anti-submarine aircraft. However, after the Allies deployed escort aircraft carriers in 1943, the war losses dropped significantly, which showed that anti-submarine aircraft were the natural nemesis of submarines.
The Fletcher-class destroyers were American destroyers developed in 1940 and were 114,000.76 meters long, 12.04 meters wide and 5.5 meters in draft. The powertrain can provide 60,000 horsepower, a maximum speed of 37 knots, a standard displacement of 2,100 tons, and a full load displacement of 3,050 tons. The radar and sonar installed by the Greyhound in the film played a crucial role in the discovery and positioning of German submarines.
The Fletcher-class destroyer was the first destroyer to be equipped with radar. Each ship is equipped with a full service radar system, including air search radar and sea search radar. The air-to-air search radar equipped with the Fletcher-class is mainly sc-1 type, and the maximum air-to-air detection distance is 120 kilometers. The sonar of Allied ships was mainly used for submarine attacks rather than submarine searches. For the Allied main transport fleet in the Atlantic, the use of sonar to search for submarines was largely meaningless, because the noise of the ships was too loud when the ships sailed, and the sonar technology at that time was not good and the range was not very far. Action is limited, so it is ineffective. Look for submarines. The main means for the Allies to fight U-boats was to use long-range patrols. Using visual, radar and patrol aircraft search methods, search for submarines sailing or snorkeling on the surface of the water, and attack after discovery. The main role of destroyers and frigates is to escort transport ships, intercept them when submarines attack, reduce fleet losses, and destroy attack submarines as much as possible. Of course, they also play a very important role in radio detection, because wolf pack tactics require frequent use of radio to communicate with other submarines, notify the target location, and then wait for other submarines to launch swarm attacks. This radio communication process can be detected and intercepted. Once the escort ship finds frequent radio communications at close range, it can be confirmed that the U-boat has found itself and can actively search or call the aircraft to search.
In the film, the second U-boat uses something new from the time in its confrontation with greyhound deceptive baits, called the "thrower" in the film, which is a fifteen-centimeter-diameter bait bomb containing lithium hydride, and the spring is released after being shot out. Lithium hydride releases a large number of bubbles when it encounters seawater, which can last for twenty-five minutes, seriously interfering with sonar detection. The injector of this bait is indeed called a blast wheel.
In the film, the most criticized by professional film critics is also the most talked about by military fans. It completely restores the day-to-day operations of the U.S. Navy, such as the captain played by Tom Hanks. Command, which has rarely appeared in previous naval battle films, is actually the basis of naval tactics. From sonar reports to radar detections at the center of the war, the chain of command is repeatedly passed through in naval battles. If the information doesn't transfer well, it could face disaster. With the retelling of the messenger and the repeated confirmation of the relevant personnel, a lot of tension is added to the film, and the film is full of realism.
The Battle of the Atlantic lasted five years and eight months. Britain and the United States invested a total of three thousand warships and eight thousand aircraft; ensuring that allied ships completed the crossing of the Atlantic with three hundred thousand ships. Germany invested a total of thirty-seven surface warships and one thousand one hundred and sixty submarines. The Allies and Neutrals lost a total of 2,840 ships, weighing a total of 21 million tons, and 60,000 seafarers were killed, of which 68.1 percent were sunk by submarines; 13.4 percent were sunk by aircraft, 7.2 percent were sunk by surface ships, and 6.5 percent were sunk by surface ships. Germany lost seven hundred and eighty submarines and thirty thousand sailors, accounting for sixty-seven.2 percent of the one thousand and sixty submarines that went into battle.
Friends who may like the history of World War II, when reviewing Germany's various strategies and operations, will emphasize that if Germany's submarine warfare was in the first forty-two years of the Anglo-German War, the submarines were enough to say that it was really possible to suffocate the British, but I think the explosive speed of Germany and the United States is not an order of magnitude, and sneak attacks and hunts are always a competition of one foot high and one foot high. It can be seen that in the forty-two years of Germany's most glorious record, the Allies did not shrink back because of huge losses. And I think that in the middle and late stages of the war, not only because of the superiority in the development of technical weapons, but also because the German army lost many excellent submarine officers and men in the early stages of the war. Very high-grade weapons require very highly qualified personnel. I personally think it's second only to pilot training. However, Germany's population and outbreak rate lag far behind the rate of consumption.
Naval battles in the Atlantic during World War II are not as famous as the Pacific Wars, but they are no less intense and significant than any naval battle in World War II. The length of the time span and the great losses are also the highest in World War II. However, through this battle, it is shown that the victory or defeat of a maritime war is the result of repeated contests between the military, economic, political, diplomatic and other forces of the two warring sides. Breaking diplomatic relations at sea and maintaining war have an important strategic position in modern warfare.