When World War II swept through Europe and pulled in all of the major powers around the globe, it left oceans of blood in its wake. Having taken approximately 50 million lives, it's said to be the bloodiest war known to history [source: Chatterjee].
The war began with German dictator Adolf Hitler's rise to power and hostile invasion of Poland in 1939. Germany, Italy, Japan and other countries made up the Axis powers. The opposing side was the Allies, which consisted of powerful nations like Britain, France, the USSR and the United States. The conflict didn't end until 1945, after the U.S. bombings of Hiroshima and Nagasaki.
When you consider that these world powers were using technologically advanced explosives and weapons built to be efficient killing machines, it comes as no surprise that the war featured some of the bloodiest battles ever. We've gathered some of the most significant battles of violent conflict, each one costing thousands -- and in some cases millions -- of lives.
As we go over each one, take note that the exact numbers of casualties (which can include not only the number of dead, but injured, sick and missing) are disputed and vary among sources. Also, the term "battle" isn't strictly defined. Some use it only to refer to shorter conflicts that take place in a confined area, while others have a looser definition that includes large-scale operations or military campaigns.
We'll start with one of the bloodiest battles in the Pacific theater.
Although most of the battles in this list took place in the European and Russian theaters of the war, the island of Okinawa was the site for one of the bloodiest battles in the Pacific theater. This conflict, which is considered the biggest land-air-sea battle ever, spanned several months and claimed the lives of thousands on each side [source: Feifer].
Controlled by the Japanese, Okinawa (the largest of the Ryukyu Islands) was a key strategic location that the United States sought in its campaign against Japan. The U.S. forces invaded in March 1945. The Japanese responded with devastating air attacks using kamikaze pilots who intentionally steered their planes into U.S. ships. The Japanese also held back on launching their major ground counterattack until U.S. troops got more inland and out of range of naval support [source: Encyclopaedia Britannica]. Although the U.S. troops eventually prevailed, it took months of bitter fighting that didn't end until June.
More than 100,000 Japanese soldiers and 12,000 American soldiers died in Okinawa. This isn't including those wounded, which for the U.S. forces amounted to 36,000 soldiers [source: Encyclopaedia Britannica]. Tragically, some estimate that Okinawan civilians made up 150,000 of the dead left in the battle's wake [source: Feifer].
As one of the most famous battles ever, the invasion of Normandy was also among the bloodiest. This long-awaited Allied invasion into Nazi-occupied territory was a pivotal victory for the Allies.
The offensive launched on the morning of June 6, 1944, now known simply as D-Day. British, U.S. and Canadian troops landed on five beaches along the shore of Normandy. From the early morning hours, the Allies used air support to bomb the German troops stationed there. Although it was meant to be a surprise, German forces were somewhat prepared for an invasion and didn't go down without a gruesome fight. As the months wore on, the Allies fought for control of Norman towns, including Cherbourg and Caen.
The whole invasion spanned several months and lasted until the end of August. Casualties were high on both sides: Estimates peg German casualties at a staggering 320,000 (30,000 dead, 80,000 wounded and the rest missing) and Allied casualties at about 230,000 (more than 45,000 dead) [source: Encyclopaedia Britannica].
After the invasion of Normandy, things were looking up for the Allied troops as they marched into Belgium. They hoped to find a significantly weakened Nazi defense. Unexpectedly, however, the Axis forces launched a huge counteroffensive on the Allies as they were making their way through the thick Belgian forest in the bitterly cold winter of 1944.
In December 1944, Allied air support was grounded as a result of the bad weather, and Hitler's forces seized the opportunity to strike. For a few weeks, the Nazi troops and their tiger tanks prevailed, having pushed Allied forces back several miles. However, by Christmas, the tide had turned, and by mid-January, the Allies had fought their way back to their original position in the Ardennes Forest. The battle turned out to be a failed last-ditch effort on Hitler's part to regain an upper hand in the war.
Some have called this battle the bloodiest for Americans, as 19,000 U.S. soldiers lost their lives and more than 70,000 were wounded or went missing. For comparison, of the 12,000 British casualties, 200 were killed [source: Goldstein]. The Germans likewise suffered heavily with about 100,000 casualties [source: Miles].
By mid-1942, Nazis set their eyes on Stalingrad, a city that stretches along the Volga River. It was an industrial city that not only produced military supplies but also would serve as a key strategic hold in their invasion of Russia. The Nazis attacked the city with air raids and came on the ground with more than 150,000 soldiers and about 500 tanks [source: Roberts].
The Nazi commanders expected a relatively easy win, but a relentless Soviet army held strong. The battle raged for about five months as streets filled with machine gunfire. By November, Soviets launched a significant counterattack to keep the invaders at bay. The German forces exhausted, they surrendered (against Hitler's wishes) by February 1943.
This was a decisive battle that changed the tone of the war in favor of the Allies. And although the Soviets won, they also suffered more casualties than their enemies in the process. Axis forces had about 800,000 casualties, compared to more than 1 million on the Soviet side. In addition, about 40,000 civilians died in the conflict.
Like we mentioned earlier, historians and scholars sometimes use the term "battle" loosely. Keep this in mind when we tell you that the Battle of Leningrad, also known as the Siege of Leningrad, was fought over the course of years -- a span of time commonly rounded up to 900 days. It lasted from September 1941 to January 1944.
Not just soldiers, but anyone who was able -- men, women and children -- were called upon to help build protection along the city's borders that would deter the approaching Nazi tanks. Although it took years of fierce, violent warfare, the Soviet army and civilians were able to hold back the Germans and prevent total destruction of the city.
As you might expect from a battle that lasted longer than some wars have, the number of deaths was astronomical. Most horrific is that more than 1 million civilians lost their lives as a result of the conflict [source: Collins]. This number made up about one-third of the local population at the time. Some fell victim to warfare directly, others from disease, freezing to death or starvation -- Nazi forces blockaded the city to prevent the people from receiving supplies. The Soviet army lost more than 1 million lives as well, not including more than 2 million sick or injured [source: Glantz]. The number of German casualties is disputed, but ranges in the hundred thousands.
The invasion of Poland was the first battle of World War II and was actually a running conflict -- a string of many battles fought through the country to Germany's east and Russia's west. But because it was frequently difficult to discern where one battle stopped and another started, many historians lump the invasion of Poland into one great, bloody rout.
Basically, the invasion was the result of a pact between Germany and Russia to overrun and divide Poland. Poland, trapped in the middle between these two ambitious powers, never really had a chance.
On Sept. 1, 1939, the Germans attacked Poland from the west, and the Polish forces retreated directly into the hands of the Russians, who were waiting to attack from behind. Caught in the crossfire of this secret pact between their neighbors and awaiting aid from France and the United Kingdom that never came, 65,000 soldiers from Poland's 950,000-strong military force were killed, more than 133,000 were wounded and the rest were considered captured. Fifty-nine thousand soldiers from the USSR and Germany were killed or wounded [source: The Atlantic Monthly].
The marriage between the USSR and Germany soon soured, and Germany took the whole of Poland and a swath of eastern USSR that extended nearly to Moscow. This meant that in 1944, as the Third Reich crumbled, the USSR was particularly enthusiastic about sticking it to its one-time ally. The bloody task of chasing Germany from eastern USSR and Poland lasted from June 22 to Aug. 19, 1944 and was called Operation Bagration.
In a way, it was the ultimate table-turning on the German forces. The USSR's push through Poland coincided with the Allies' push through France, which meant that German forces had to fight ahead and behind -- just like Poland had been forced to do in 1939.
In fact, the operation was the manifestation of an interesting, fairly new Soviet strategy called Deep Operations (among other names). With this strategy, instead of consolidating their hold on wide areas of land taken from Germany, Soviet troops stayed relatively narrow in order to push deep into German territory. Striking deep at the heart of Nazi Germany, the Soviets hoped, would do more strategically than consolidating gains at the edges.
So it was that in mid-August 1944, the Soviets reached the outskirts of Warsaw, Poland, just as the Polish resistance had itself risen up against the Nazis. All told, Operation Bagration took 350,000 German and 765,000 Soviet troops [source: History.net]. But even with the Third Reich in its death throes, it would take many more thousands of Allied and Axis lives before the war ended.
Though the number of troops killed on Iwo Jima doesn't rival some of World War II's other battles, the battle is notable for the percentage of troops killed. On Iwo Jima, Japanese troops fought to the death -- of the nearly 22,000 Japanese troops who started the battle, only 216 were taken prisoner. The rest were killed. With 26,000 U.S. troops killed or injured, the Battle of Iwo Jima is the only clash of World War II in which U.S. casualties outnumbered Japanese casualties [source: Military.com].
The battle began on Feb. 19, 1945, and it was immediately clear that U.S. troops were facing a resolute and well-prepared enemy. The island, whose name means "sulfur island" in Japanese, smelled like just that, and concealed a labyrinth of underground tunnels. Troops recalled that after fighting a bloody battle to take a hill, they would soon find themselves facing an enemy that had tunneled beneath them to the rear. Within the island's highest mountain, Mount Suribachi, at 556 feet (169 meters) above sea level, the Japanese had dug a seven-story base filled with weapons and supplies [source: History.net].
The battle for this small island took 36 days [source: History.net]. In fact, the classic picture of U.S. Marines raising a flag on Mount Suribachi was taken in the early days of the battle, with still a month to fight. As with the Vietnam War, the U.S. troops were adept at taking a defined objective like the Mount, but had more difficulty mopping up the less defined targets of underground and embedded troops.
In the early spring of 1945, the Soviet Army streamed toward Berlin, where Adolph Hitler was dug in amid the ramshackle remains of his once-great Third Reich. A trapped animal has two options -- play dead or fight -- and Hitler chose the second. Fueled by German propaganda that highlighted the wake of destruction left by Soviet troops on their march through Prussia, the German people felt their only option was to fight to the death alongside their megalomaniacal leader.
As Soviet troops encircled the city, Hitler readied Wehrmacht (defensive forces), Volkssturm (militia), Waffen-SS (elite police force), and thousands of Hitler Youth (boys age 14 to 18) for a desperate last stand. In all, there were 300,000 German troops. The Soviet forces, on the other hand, numbered in the millions [source: BBC].
On April 20th, 1945 the Soviet shelling began. If softening the target was the Soviet objective, they could take heart in knowing the target was already plenty soft: Years of allied bombing had left the German city of Berlin looking more like the idiomatic cheese from Switzerland. And so, only a couple days after shelling started, it effectively stopped as Soviet troops took the city.
Hitler and many of his followers committed suicide, and the Battle of Berlin officially ended on May 2, 1945. However, the fear of surrendering to the Soviets was so strong that the Germans continued fighting in hopes of breaking through the Soviet siege in order to surrender to Western forces instead of the USSR.
The cost to the Soviets was more than 70,000 men (many believe that number could have been fewer had Russian generals not been so eager to capture Berlin before the United States) [source: BBC]. Nearly 250,000 Germans died.
In terms of bloody World War II battles, it's hard to leave the Eastern Front, where the clash of Germany and the USSR left nearly 15 million military dead and at least double that number of civilians. But let's leave Germany and the USSR alone for a moment to look at a very interesting World War II battle -- the Battle of Singapore.
The island of Singapore was the gold standard British outpost in Southeast Asia, but the story really starts with China. In 1942, the Japanese were deeply mired in the Second Sino-Japanese War and to their troubles the Allies added a trade embargo. Japan needed resources, and its best shot at these resources was in Southeast Asia.
In 1941 (nearly simultaneous with the Japanese attack on Pearl Harbor), the Japanese beat the British out of Malaya and then turned their sights on Singapore. The story was this: Despite being outnumbered more than two-to-one, the Japanese had superior air power and military intelligence. It was a battle of a tactical David against a technologically inferior Goliath and unfortunately for the Allies, the British (and their Australian allies) were the bigger, slower party.
Aided by air supremacy, the Japanese exploited holes in the defense to infiltrate the island and in exactly a week -- Feb. 8 to Feb. 15, 1942 -- had taken it. Five thousand British and Australian troops were killed or wounded, but the real toll on Allied troops were the 80,000 who went to Japanese prison camps, the vast majority of whom would never make it home. In addition, after the battle, the Japanese massacred ethnic Chinese on the island [source: Asia-Pacific Journal].
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