The Physics of War (32 page)

A new and significantly better system was developed and put into operation in January 1941. It was called the ground-controlled intercept (GCI) system. In this system the antenna was rotated, allowing for a two-dimensional representation of the airspace around the operator. Incoming aircraft appeared as bright dots on a screen, similar to what we see today. The indicators, which were called plane positive indicators (PPI), were a significant improvement over those used in CH. The position and altitude of a plane could now be determined quickly.

Then, in 1939, Edward Bowen and his team developed a small radar system that could be used in airplanes and submarines. It was called the Air Interception (AI) system. It was quickly placed in many of the British aircraft and submarines, and it gave an even better fix on incoming German planes. The Germans tried to avoid it by flying only at night and in poor weather. This had no effect on the radar system, although the British pilots sent out to attack them had more trouble locating them.

In early 1940, however, the cavity magnetron was invented by John Randall
and Henry Boot, and it revolutionized radar. It had been known for years that if short-wavelength radiation could be used in radar systems, it would significantly improve the images. But as they decreased the wavelength, the power of the system decreased. This changed with the introduction of the magnetron. With it, “centimeter” radar was possible for the first time, and the power of the new units was much greater. There was still a problem, however; large numbers would be needed, and Britain was in no position to develop and produce them. As we saw earlier, this led to the Tizard Mission in September 1940, which resulted in the manufacture of a large number of magnetrons in the United States.
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High-quality radar units could now be mounted in airplanes, ships, and submarines, and they were extremely effective. With their high resolution they could detect objects as small as submarine periscopes. And this quickly blunted the effectiveness of the German U-boat program. Large numbers of U-boats were hunted down and sunk, until finally the Germans withdrew their fleet.

Further advances in radar continued throughout the rest of the war. In 1938 the coastal defense (CD) system was developed. It was not an airborne radar unit, so it could be made much more powerful.

Several defenses against radar were developed during the war, and they were used by both sides. Radar “jammers” were developed that transmitted radio signals of the same frequency as the radar. The jammers were used to saturate the receiver with strong signals so that it couldn't detect properly. “Chaff” was also used. It was a cloud of lightweight strips of metal of a specific size that potential radar targets could deploy to interfere with the incoming signal. The radio receiver would only see a huge cloud when it was used.

But luckily for the British, the Germans didn't take radar very seriously, and they never put a large effort into developing it or protecting against it.

THE BATTLE OF BRITAIN

Soon after France surrendered, Germany turned its attention to England, and what took place over the next couple of months was one of the most famous battles of World War II. And it was totally an air battle. Hitler knew that for total control over Europe he would eventually have to attack England. In particular, he would have to land large numbers of troops on British shores. But while they were landing they would be under constant attack from Britain's powerful navy and also from its air force. He knew that the losses would be staggering and that he had to disable the RAF (Royal Air Force) and the navy before beginning his Operation Sea lion, which was his code name for the land invasion of Britain.
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Hermann Göring, the commander-in-chief of the Luftwaffe, assured Hitler that his airplanes could defeat the RAF in the south of England within four days and destroy the rest of the RAF within four weeks. Hitler was therefore overcome with confidence, and he scheduled Operation Sea lion for September 15. And there was no doubt that Germany had an overwhelming superiority in numbers: over 4,000 aircraft compared to Britain's 1,660. Included in this number for the Germans were 1,400 bombers, 800 fighter planes, 300 dive bombers, and 240 twin-engine fighter bombers. The RAF had mostly Spitfires and Hurricane fighters.

The battle began on July 10, 1940, with the Luftwaffe bombing coastal shipping centers and ship convoys. But by the end of July, British fighters had shot down 268 German planes and had lost only 150. As a result, the Luftwaffe switched to attacking airfields, operation rooms, and radar stations. They hoped, in particular, to disable the British radar system. The Stuka had been used extensively in the German blitzkrieg attacks, and it had been particularly effective when used over Poland, France, and Belgium, where there was little defense against it. But it had never encountered a fighter like the Spitfire, which had a top speed of 350 miles per hour compared with the Stuka's top speed of approximately 200 miles per hour. Furthermore, the Stuka was much less maneuverable, and its ability to dive was not an advantage in an air war. By the middle of August, nearly all the German Stukas had been destroyed by Spitfires and Hurricanes. Göring quickly pulled the few remaining ones out of the war.
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Britain's big advantage (aside from radar): the Spitfire. It was faster and more maneuverable than most German planes.

Germany may have had an advantage in numbers, but Britain had several important advantages. German fighters barely had enough fuel to get to England and back; they were used to protect the bombers, but they had to return soon after the bombers were over England, and this left the bombers vulnerable to attack. As a result, large numbers were shot down. Furthermore, German fighters frequently ran out of ammunition over England and had to head for home quickly. British planes could easily land and quickly reload their guns. And of course the biggest advantage the British had was their radar detection system. The RAF therefore knew at all times where the German bombers and fighters were, but the Luftwaffe pilots could only guess where the British were.

After August 23 the Luftwaffe stopped attacking seaports and radar sites and switched to night raids on cities—London, in particular. But the Germans continued losing planes at a rate of almost two to one: 1,000 German planes to 550 of the RAF's planes. And on September 15 the Luftwaffe lost sixty planes to the RAF's twenty-eight in a single day. Two days later Hitler postponed the invasion of Britain indefinitely. But the indiscriminate bombing of the larger cities continued. In the end, both sides had taken heavy losses, but the German losses were much greater. And finally, about the middle of October, the raids ceased except for an occasional bombing. The Battle of Britain was over and the British had won. But the war was far from over.

AMERICAN ENTRY INTO THE WAR

The United States entered World War II following the Japanese bombing of Pearl Harbor, but even before 1939 most Americans realized they would eventually be involved in the war in Europe. The trigger, however, came on December 7, 1941. Over a period of four hours six Japanese aircraft carriers sent waves of torpedo planes, fighters, and dive bombers over Pearl Harbor. Given the simmering political tensions between the United States and Japan, there was some expectation among American military leaders that the Japanese might attack. Nevertheless, the US forces were caught completely off guard. As a result, the Japanese planes were able to destroy or severely damage eight battleships, ten smaller warships, and two hundred thirty aircraft, while killing 2,400 US personnel.
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The following day the United States declared war on Japan, and since Hitler and Mussolini had just signed a pact with Japan, Germany and Italy declared war on the United States. Although Japan didn't follow up its attack on Pearl Harbor, it did attack the US air base near Manila in the Philippines, and the
Japanese army invaded and trapped large numbers of Americans and Filipino forces in nearby Bataan, leading to the infamous Bataan Death March, during which thousands of Americans and Filipinos died. General Douglas MacArthur escaped to Australia and vowed to return. The Japanese continued their invasion, seizing the Dutch East Indies, and then the islands of Tulagi, Guadalcanal, and the Solomon Islands. They seem almost unstoppable.

What was left of the United States Navy first met the Japanese in the Coral Sea near the Solomon Islands. During two days of combat the Japanese lost a small carrier, a destroyer, and several smaller ships, but the United States lost a carrier and a destroyer, so the battle has generally been considered a draw. But in the process the Americans stopped the invasion of an island that would have allowed the Japanese to strike Australia. It was also an important battle in that the Americans learned a lot about Japanese tactics, and this would help them later in the war.

One of the major naval battles of the war came in June 1942. The Japanese admiral Yamamoto was planning a large offensive near Midway Island. He hoped to trap and destroy most of the American fleet in a quick and decisive battle, but American intelligence, which had managed to decode Japanese messages, knew what he was planning. This allowed American admiral Chester W. Nimitz to set up a web of decoy tactics and plan an ambush. And when the battle ended, the Japanese had lost four carriers and all the airplanes that had attacked Pearl Harbor, along with a large number of Japanese pilots. In turn, the Americans had lost only one carrier. This was a major defeat for the Japanese, and a turning point in the war in the Pacific. The American navy now had clear-cut superiority over Japan's navy.

The battle of Leyte Gulf in the Philippines, which came in October 1944, was one of the largest naval battles in history. It was also a decisive victory for the US Navy, which sank most of the remaining Japanese fleet. What remained of the Japanese navy finally retreated back to Japan.

Over the previous few years Japan had occupied a large number of islands in the South Pacific, and American forces began a strategy known as island hopping, in which they targeted islands that could support airstrips that would allow them to get closer and closer to Japan itself. At the same time they applied their air power to cut off all supplies to Japanese troops on the various islands. The Japanese, however, had dug in, and many of them were in bunkers and caves. Furthermore, American marines soon found that most Japanese preferred to fight to the death rather than be captured. So the fighting was difficult.

Hand-fought battles at Guadalcanal, Tulagi, the Marshall Islands, Iwo Jima, and Okinawa followed. In most cases the Japanese fought until the last man was killed. Furthermore, Japanese pilots were now flying kamikaze missions in
which they would commit suicide by flying their planes into American ships. In this way they managed to sink thirty-eight ships and damage many others.

Because of this, the American high command decided that an invasion of mainland Japan would lead to the loss of too many American lives, with the Japanese refusing to the end to give up. President Truman therefore ordered the dropping of atomic bombs on Hiroshima and Nagasaki in August 1945, and within a short time the Japanese surrendered. We will discuss this in more detail in the
next chapter
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Turning now to the war in Europe, the first American operation was in November 1942, when American and British troops landed in North Africa. They stopped the German advance on Tunisia, and by May 1943 they had defeated the Germans, capturing over 275,000 men in the process. Along with the British, they then turned to what they believed to be the weakest link of the German and Italian defense, namely Sicily. In July 1943, a large amphibious invasion was unleashed, and in a little over a month Sicily was under Allied control. The Allies then turned their attention to the Italian mainland. American troops landed in Italy in September, and Italian troops surrendered almost immediately, but a large number of German troops were now in Italy, and they continued to fight through the winter. But in June 1944, Rome fell, and soon the Allies had occupied most of Italy.

Meanwhile, in England the largest amphibious attack in history was being planned. The operation, which began on June 6, 1944, consisted of 4,600 ships and over a million troops. Under the command of General Dwight D. Eisenhower, the Allies crossed the English Channel in an effort to establish a beachhead in Nazi-occupied France. The Germans had been expecting an invasion, but they didn't know where the Allied forces would land. For two months preceding the invasion British-based aircraft had bombed airfields, bridges, and rail lines throughout France. And on the night before the landing, paratroopers were dropped inland as naval guns powdered installations along the shorelines. The various landings were given code names; the British and Canadians landed at Gold, Juno, and Sword Beaches, while the Americans landed at Utah and Omaha Beaches. The Canadian and British landings went relatively smoothly, meeting little opposition, but the Americans were met by heavy German gunfire that inflicted many casualties. Within five Days, however, sixteen Allied divisions were in Normandy, and the drive to liberate Europe was under way. By August 25 Paris was captured, as the Allies continued their push toward Berlin.