World War I was a true world war. It was fought around the globe from German colonies in Africa to the disintegrating Ottoman Empire in the Middle East and throughout the oceans of the world. On the Eastern Front, a crumbling Russian Empire in the throes of revolution took huge numbers of losses. In just the summer of 1916, the Brusilov Offensive caused around a million casualties, averaging thousands a day. However, it was fighting on the Western Front that was truly horrifying. Of the deadliest battles of World War I, seven were on the Western Front. This doesn’t mean that other fronts around the world were any less horrifying, just that the most industrial nations of the world focused their attention and their biggest guns on the Western Front.
Modern warfare casualty numbers are often deceiving, as they record how many soldiers can no longer fight and not how many were killed. Casualty figures include those Killed In Action (KIA) but they also count those Wounded In Action (WIA), Missing In Action (MIA) and those taken Prisoner of War (POW), as these soldiers are no longer on the unit’s roll call. This is further complicated because a lot of nonfatal wounds that occurred on one day will eventually, days later, kill the soldier. Prisoners offer the same difficulties, as POWs often die in the horrible conditions of prison camps. For example, during World War II the Nazis were particularly brutal to their Soviet prisoners, causing 3.3 to 3.5 million deaths, or 57% of all Soviet POWs.
World War I happened just as the world was industrializing. This new technology allowed the nations involved to apply industrialization to the slaughter of their enemies. This, and the amount of soldiers packed together in the trenches, allowed for casualty numbers that had never been seen before. Historically the most soldiers killed in a single day, for most countries, were during these battles on WWI’s Western Front.
10. Spring Offensive, or Kaiserschlacht (Germany)
Deadliest day: March 21, 1918
For four brutal years, the Allies had been fighting the central powers, the Empires of Germany, Austria-Hungary, Ottoman, and the Kingdom of Bulgaria. In early 1918 Imperial Germany knew it finally had a chance to win against the Allies. After years of war, the United Kingdom and France were exhausted. The United States had entered the conflict in 1917 but hadn’t been able to mobilize its vast resources yet. To the East fires of revolution had knocked out Russia in March of 1918. The Russian surrender freed up 50 divisions that could be refocused on the west. The Germans reasoned that they could land a death blow if they could break through the trenches of the Western Front before the Americans landed any large numbers.
To this end, the great minds of the Imperial German Council planned the March 1918 Spring Offensive, or Kaiserschlacht. The main thrust of the Offensive, Operation Michael, planned to break through the Allied lines, capture the channel ports and forcing the British out of the war. It was then hoped that the French would seek an end to hostilities. To accomplish this the Germans arranged 72 divisions of men, spearheaded by deadly stormtrooper units, against 29 British divisions and a possible 23 French divisions.
Two years earlier, the 1916 Battle of the Somme saw the Allies in 140 days of horrific trench warfare take a staggering half a million casualties, all for 98 square miles of mud around the Somme. When Operation Michael started on March 21, 1918, the Germans took almost the same ground in one day. That ground came at a price and was the German’s bloodiest day of WWI. 10,851 Germans were killed outright, and a further 28,778 were sent behind lines with wounds, and a small amount were taken prisoner for a total one-day casualty number of around 40,000 Germans.
While the Allies were pushed back they were able to retreat, prevent a breakthrough and eventually stop the German advance. When the battle ended on April 15, 1918, the exhausted Germans knew that they couldn’t replace the 240,000 casualties they took while the Allies would only get stronger as more and more Americans landed in Europe.
9. Australia and New Zealand
When the Dominions of Australia and New Zealand entered the war they were grouped together as the Australian and New Zealand Army Corps (ANZAC). The defining battle of the ANZACs and now a deep part of both country’s mythology is the brutal and ultimate failed operation against the Ottoman Empire, the Battle of Gallipoli. Even though this doomed fight cost thousands of young ANZAC soldiers no day during Gallipoli was the deadliest day for either Australia or New Zealand.
New Zealand – First Battle of Passchendaele
Deadliest day – October 12, 1917
On October 12, 1917, during the First Battle of Passchendaele the British High command ordered the New Zealand Division to capture the Bellevue Spur, a slight ridge that led up to the Belgian village of Passchendaele. The odds were stacked against the Kiwis. The artillery barrage didn’t cut the barbed wire defending the German trenches and relentless rain made the ground a wet morass that caused Allied shells to explode harmlessly. When the whistles blew and the New Zealand Division climbed out of their trenches, they did so into the gun sites of waiting Germans machine guns. October 12, 1917, is still the darkest day in the country’s military history with 847 killed in the failed Allied attack. The many battles fought over time around Passchendaele would eventually claim close to 2000 New Zealand soldiers, a huge toll for a small country with only a population of around a million.
Australia – Battle of Fromelles
Deadliest day – July 19, 1916
After the failure of Gallipoli, the Australians were transferred to Europe and their first and deadliest battle was the Battle of Fromelles which was part of the larger Battle of the Somme. Fromelles was poorly planned and bad intelligence saw that the attacking Australians were actually outnumbered by the well-defended Germans almost 2:1. Fromelles is described as “worst 24 hours in Australian history … Not the worst in Australian military history, the worst 24 hours in Australia’s entire history.” 1230 Australians lost their lives on July 19, 1916. Over the two day battle, there was a total of 7,080 British casualties, 5,533 of the losses were by the 5th Australian Division. This compares to German defenders who counted “only” around 2,000 casualties.
8. The Battle of La Lys (Portugal)
Deadliest day: April 9, 1918
The military alliance between the United Kingdom and Portugal (known in Portugal as Aliança Inglesa) is “the oldest alliance in the world that is still in force.” Yet the Portuguese were latecomers, not declaring war on Germany until March 9, 1916, and the Portuguese Expeditionary Corps (CEP, or “Corpo Expedicionário Português”) didn’t arrive on the front lines until the next year in April 1917.
Almost a year after they deployed they faced their biggest test on April 9, 1918, during The Battle of La Lys. The German Sixth Army deployed eight divisions, around 100,000 soldiers, which slammed into the Portuguese Second Division of around 14,000 active soldiers. Despite stubborn resistance, the Germans overran the trenches, laying waste to the beleaguered Portuguese Second Division and eliminating it as an effective unit.
The CEP faced the Germans for just three days, from April 9-11. During their advance 2,000 Portuguese were WIA and the Germans took around 7,000 prisoners. Around another 600 were killed in action, mostly on the first day. During the whole of WWI, about 7,200 Portuguese died. The Battle of La Lys accounted for around 8% of that total.
7. Dinant (Belgium)
Deadliest day: August 23, 1914
When Germany entered the war it activated the infamous Schlieffen Plan. Under the plan, the Germans invaded France through neutral Belgium and Luxembourg, hoping to catch the French off guard. The invasion of Belgium took a month. Even though its Army was a tenth of the size of the German invasion force, with British and French helped the shattered Belgian Army hold off the Germans, and even keep a sliver of Belgium for the rest of the war. Throughout the war, 38,170 Belgian soldiers died. This number is split between 31.7% killed in 1914 during the German invasion, another 31.1% during the 1918 Liberation of Belgium, and the remainder during the German stalemate between 1915-17. The bloodiest battle was probably the Battle of Liège where Germany’s top secret giant guns leveled the fortifications surrounding city of Liège. Around 3,000 Belgians were killed, spread out over the 11-day battle. The war then settled down into a stalemate of trenches stretching from the sea to Switzerland. The remaining Belgian army occupied the westernmost portion and was too small to attack German lines. It largely sat out the war.
The bloodiest day for Belgians was for its civilian population. When Germany rolled over the Belgian border they were paranoid of Belgian guerrilla fighters. Stories quickly circulated in the German Army that the Belgians had unleashed illegal saboteurs (called “Francs-tireurs”). Even though the rumors were largely baseless the Germans saw enemies everywhere. Civilians were regularly massacred, there was massive looting, and whole towns were deported or just burned down. Between the start of the war in August and November of 1914, 6,427 Belgian and French civilians were killed behind the front lines. The largest massacre was in the Belgian city of Dinant. The Germans bungled a raid in Dinant and were forced out. In revenge, the Germans returned, captured the city and on August 23, 1914, 647 civilians (10% of the town) were killed on orders from the German command.
6. Battle of Delville Wood (South Africa)
Deadliest day: July 18, 1916
The South African Army had only recently arrived in Europe and the Somme would be their first battle. One of the key objectives during the Battle of the Somme was the heavily forested Delville Wood. South African military commander, Brigadier-General Henry Lukin, was ordered to take the wood at all costs. They achieved their goal and occupied the forest on July 15, 1916.
They quickly found out that that was the easiest part. Until July 19, the South Africans fought off a number of German counter-attacks. The terrible weather and constant German thrusts turned the forest into a graveyard of muddy stumps. 3,000 men of the 1st South African Brigade entered the forest. When they were relieved five days later, 143 men were still left standing. The deadliest day was July 18, 1916, when 253 South African soldiers were killed.
5. Battle of Vimy Ridge (Canada)
Deadliest day: April 9, 1917
The Canadians saw their first battle in WWI during the Battle of Neuve Chapelle in March of 1915. The British descendants that lived in the Domain of Canada were highly supportive of the war and sent thousands of men to Europe. By 1917 they formed their own Army under the command of Julian Byng. Seen as a formidable fighting force, they were assigned a daring task: to take Vimy Ridge. The German-occupied Ridge had seen multiple failed attacks. The French tried two times in 1915 and 1916. The British took over and were promptly defeated by the Germans. In October of 1916, the Canadians took over and started making preparations for an assault in the spring of 1917.
Adopting a number of technical and tactical innovations, intense training, and new artillery bombardment techniques, the Canadians launched their attack on April 9, 1917. In three days they took the ridge that thousands of French and British couldn’t. The victory was a huge achievement for the Canadians and nationalists quickly wove the win into the mythology of Canadian nationhood. Brigadier-General Alexander Ross, who had commanded the 28th (North-West) Battalion at Vimy, later said, “It was Canada from the Atlantic to the Pacific … I thought then … that in those few minutes I witnessed the birth of a nation.” This birth came at a price, with Canadian Corps suffering 10,602 casualties (3,598 killed and 7,004 wounded). The deadliest day was the launch of the battle on April 9, 1917, when 2,414 Canadians died.
4. Battle of the Somme (England)
Deadliest day: July 1, 1916
The Battle of the Somme was an immense offensive planned for the summer of 1916. After two years of trench warfare, the generals of the British and French armies were confident that total brute force would finally cause a breakthrough of the German lines. The Battle lasted from July 1, 1916, to November 18, 1916, and involved over 3 million people at each other’s throats. The British and French not only had people from their Motherlands, but they had both mobilized their respective Empires. The British had men from their Dominions as well as colonial forces like the brave veteran soldiers of the Indian Army, down to the men from the small Caribbean island of Bermuda. France, too, was utilizing its colonial forces and even using the French Foreign Legion. The Battle of the Somme is also famous for being the first time tanks were used.
Five days before the July 1, 1916, start date the British and French pounded the German lines with 1.5 million shells and another 250,000 shells were fired on July 1 itself. However, the Germans were often safe in their sturdy entrenchments. The massive shelling didn’t even cut a lot of the barbed wire entanglements. When the bombardment stopped, 100,000 British charged the German trenches in the first wave and were quickly mowed down by German machine guns. On the first day of the battle, British casualties totaled 57,470, with 19,240 dead. It was the worst day in the history of the British Army. When the Battle of the Somme ended five months later, it cost both sides about 1,000,000 casualties.
3. Beaumont Hamel (Newfoundland)
Deadliest day: July 1, 1916
Newfoundland is now an island province of Canada, but during the war it had a population of 240,000 and was a semi-independent Dominion of the British Empire. It sent its own men to fight under the command of the British. The Royal Newfoundland Regiment arrived on the front in April of 1916. They faced off against a German army that had spent months fortifying their positions. The British, in preparation for the huge July 1, 1916, Somme offensive, had tunneled under the German front lines and planted large amounts of explosives. The one planted opposite the Newfoundlanders, the 40,000 pound Hawthorn Mine, went off at 7:20 a.m. as planned but the huge crater it caused was quickly occupied by surviving Germans before the British could take advantage of it.
In the fog of war, the British high command thought they were on the brink of a breakthrough and unknowingly ordered another push against a line of Germans that were prepared, dug in, and ready for them. At 8:45 a.m. the Newfoundland Regiment got their orders to advance but they couldn’t use the support trenches to move closer to the German lines because they were filled with the Allied dead and wounded. Anxious to push forward, Lieutenant Colonel Arthur Lovell Hadow ordered the men to leave the safety of the trench and charge over open ground. When the Newfoundlanders climbed out, they were the only movement on the front lines and easy targets for the Germans. Of the 794 men who started the attack only 68 were able to show up at roll call the next day, a casualty rate of about 90 percent. 374 were wounded, 14 of whom would die days later, and 310 were killed outright on that day. The unit was effectively wiped out. Of the hundreds of thousands of men involved in battle on July 1, only one other unit had a worse casualty rate.
The loss of so many many men was a huge blow to the island of Newfoundland and July 1 was designated a day of mourning. Decades later when Newfoundland joined Canada in 1949 it inherited Canada’s birthday, which is also on July 1. Tradition now follows that on the morning of July 1 they remember the WWI sacrifice of the Royal Newfoundland Regiment, while in the afternoon and evening they celebrate Canada’s birthday.
2. Meuse-Argonne Offensive (United States)
Deadliest day: October 4, 1918
The United States didn’t enter the war until April 7, 1917, and basically had to build the American Expeditionary Force (AEF) from the ground up. Trained military units didn’t start arriving in Europe until the fall of that year. While they were late, they did have huge resources. A major component of the Hundred Days Offensive, the last offensive push of World War I, was the American Meuse-Argonne Offensive. It was the largest battle in United States military history, involving 1.2 million American soldiers. The battle lasted from September 26, 1918, to the armistice that ended the war on November 11, 1918.
Many legends were born from these 46 days of Battle including the Lost Battalion. The Lost Battalion refers to a unit of Americans who were totally surrounded by German Forces from October 2-6 1918. Of the 554 men who first became surrounded only 194 were finally rescued, the rest being KIA or taken prisoner. Another legend and future American President, Harry S. Truman, was also present during the battle. In four days of fighting, his unit (the 35th Division) suffered 8,023 casualties out of 27,000 men, “the highest daily loss rate of any American division during the war.”
For the Americans, the Meuse-Argonne Offensive was the bloodiest of the war. During the battle, the largest amount of soldiers wounded in action on a single day was 8,358 on September 29, 1918. On the same day, 383 Americans died but the largest amount of Americans dead on a single day was 418 on October 4, 1918. More tragic would be the events of the last day of the war. The American generals knew a few days before that the war would end on November 11, 1918, yet they still ordered an offensive on the same day. A post-war investigation found that this senseless order cost 320 Americans their lives, and another 3,240 were seriously wounded for a war that was already over.
Shockingly, 418 dead or 8,358 wounded wasn’t America’s deadliest day. On September 17, 1862, during the American Civil War, Union and Confederate armies smashed into each other during the Battle of Antietam. The result was 22,717 dead, wounded, and missing on both sides, 3,675 of which were KIA. It was the single bloodiest day in American history.
1. Battle of the Frontiers (France)
Deadliest day: August 22, 1914
Throughout the war, France suffered immensely. A large portion of the front lines was fought in France. This meant that the battles destroyed French farmland, villages, and towns while even more rich farmland was occupied by the Germans. In addition, on the battlefield France had taken huge military losses. After the war, the Germans claimed that causing huge numbers of casualties was the goal of the Imperial German war plans. Infamously, a German commander stated that the purpose of the 1916 Battle of Verdun was the industrial slaughter of France’s fighting men so that “the forces of France will bleed to death.” It got so bad along the French lines that in 1917 there was a series of mutinies that were barely contained by the French military authorities.
While there were over half million casualties at Verdun, France’s bloodiest day was years earlier at the start of the war. In the summer of 1914, the German armies slammed into French forces along multiple points of the Franco-German border. On August 22, 1914, circumstances born from the chaos of war saw five armies involved in 15 independent assaults. The sheer number of soldiers involved guaranteed huge casualties. On this one day, August 22, 1914, over 27,000 French died trying to stop German divisions from moving on Paris. Finally, with the British arriving in France the Allies were able to force a halt to the German advance and at the Battle of the Marne on September 6, 1914, they were able to save Paris and push the Germans back. Despite horrible battles throughout the war, August 22, 1914 still remains “France’s highest ever death toll in a single day.”