World War I was a global conflict on a massively lethal scale, involving battles and countries in most continents. The death toll for the four-year war topped 9 million.
Called the Great War when it happened, the war was the culmination of a series of intersecting alliances and desires for expansion, most stemming from the end of the Napoleonic Wars, for which the Congress of Vienna sealed the deal. Napoleon Bonaparte met his final defeat at Waterloo on June 18, 1815. As a result, the great powers of Europe gathered to cement a peace.
As it name suggests, the gathering took place in Vienna. After a series of negotiations, the major powers emerged with agreements that, among other things, enlarged some powers at the expense of others, in an attempt to maintain a balance of power in Europe.
A series of revolutions in 1848 sent shockwaves through the major powers for a year or so. A series of wars in the second half of the 19th Century created more upheaval. Most notable of these was the Crimean War, a struggle between Russia on one side and several of the major European powers on the other.
The unifications of both Germany and Italy in 1871 raised alarm bells in the other major European countries, most notably France. The unifications came in the midst of the Franco-Prussian War, a major victory for the Germanic states. Prussia had, a few years earlier, scored another quick victory, against Austria, which resulted in the devolution of the Austrian Empire into the Dual Monarchy of the Austro-Hungarian Empire.
From these struggles, Germany emerged as a major power, in some ways even more powerful than France, Russia, or Great Britain.
Hemmed in by the newly created Germany and Italy, Austria-Hungary sought to expand southward, in the Balkans. Neighboring Serbia had expansion designs of its own. The competing desires resulted in cries for assistance. Austria-Hungary had originally formed the League of Three Emperors, with German Kaiser Wilhelm I and Russian Tsar Alexander II. Russia abandoned the League of Three Emperors and pledged its loyalty instead to Serbia, promising to attack whoever declared war on Serbia. Germany and Austria-Hungary pledged to support each other and joined with Italy to form the Triple Alliance. In response, Great Britain and France patched up their longstanding differences enough to form the Entente Cordiale and then joined with Russia to form the Triple Entente. In addition, Great Britain had a mutual defense treaty with Belgium.
As a result of the assassination of Archduke Franz Ferdinand in Sarajevo, a series of domino-like actions were taken:
Also at this time, the Ottoman Empire, frustrated by Austrian ambitions in the Balkans, threw in its lot with Germany and Austria-Hungary, resulting in the creation of what historians call the Central Powers.
The balance of power created and enhanced by the Congress of Vienna was no more.
Austria-Hungary found it tough going fighting against Serbia, so much so that Austrian troops soon found themselves fighting against a determined Russia as well. When Italy joined the war on the side of the Allies, in 1915, Austrian hopes for a quick victory (indeed, for any victory) dimmed.
Germany's battle plans had included a pre-war buildup of the German Navy, so much so that the leaders of Great Britain, owners of the world's largest military fleet, were worried about German intentions in the North Atlantic. When the war began, German submarines proved very effective at interfering with British shipments of weapons and supplies to the Continent.
Germany's plans on land consisted mostly of the Schlieffen Plan, named after Chief of the Imperial German Staff Count Alfred von Schlieffen. He was no longer head of the military when the war began, but his plan was still in place as what Germany considered its best option for avoiding a two-front war. The plan was to avoid the French forces massed across the Franco-German border by running around them, through neutral Belgium. The German military command reasoned that a quick victory, within six weeks, wasn't out of the realm of possibility, given the Prussian experience in both the Austro-Prussian War and the Franco-Prussian War. Germany also counted on the Russian army to take six weeks to fully mobilize its massive army, by which time Germany would have defeated France and been able to use the newly upgraded German rail network to move its military quickly from west to east.
So when the war began, Germany moved quickly to implement the Schlieffen Plan, except that a modification to the preferred lightning-quick troop movements resulted in the German troops getting bogged down in northern France and unable to make major headway, certainly not within a six-week timeframe. As well, Russia mobilized its armed forces more quickly than anyone expected, causing headaches in the military commands of both Germany and Austria-Hungary.
Germany moved one of its main armies eastward, by rail, and scored a victory at the First Battle of Tannenberg. But the delay in full implementation of the Schlieffen Plan, coupled with the loss of one of the main armies, left Germany short of a quick victory in France. The German advance was stopped east of Paris at the first Battle of the Marne. Allied forces drove German forces back dozens of miles. Both sides then tried to move north to outflank each other. (This was the so-called "Race to the Sea", which ended with the First Battle of Ypres.) Neither side gained an advantage until they were both out of real estate; then, both sides settled in to dig trenches. These were miles and miles of connected defensive positions, with heavily armed troops ready to fire at a moment's notice and barbed wire out front to prevent an enemy's sneak attack.
The result was very little ground gained for most of the war. In battle after battle, both sides sent troops from defensive positions inside underground trenches into "no man's land" in hopes of taking ground away from the enemy, who were ensconced in heavily fortified positions and armed with large amounts of ammunition. Millions of men died on both sides.
At Christmas during the first year of the war, both sides engaged in the Christmas Truce, a meeting in no man's land to exchange pleasantries and even play a game of soccer. It was the only such truce during the four-year-long war.
The next three years were dominated by attack and counter-attack, at places like Verdun and Ypres and the Somme. These battles lasted for months and resulted in nothing so much as mass casualties. Certainly, very little ground was gained by such attacks and counter-attacks. At the Second Battle of Ypres, Germany first used chemical gas against French and British troops. The Battle of the Somme was the first to feature a mass attack by tanks, a relatively new weapon of war. They were relatively ineffective, however.
The Battle of the Somme is a striking example of the kind of futility and mass casualties that so marked the Western Front of the Great War. British forces bombarded German positions for eight days, with the intent of destroying the German position, barbed wire and all. British commanders planned for the attack to be so successful that British troops would be able to walk across "No Man's Land" and encounter little opposition from the expected-to-be-decimated German forces. That wasn't the case, however. German troops had built quite sturdy bunkers and hid in them until the bombardment ceased, then unleashed their well-stocked gun batteries at the attacking British forces. The British advance was stymied in full force, with British losses on that first day of attempted land attack totalling more than 58,000. The battle, which stretched along 16 miles of disputed territory, dragged on for months before snow in November halted the fighting altogether. In the end, British and French forces had gained control of 7 miles of territory, at the cost of 620,000 lives. German losses topped 500,000.
The Battle of the Somme was an attempt in part to relieve German pressure on Verdun, another epic battle that lasted for nearly 300 days and claimed the lives of nearly 1 million in total. In the end, German troops did not seize the French fortresses at Verdun. The battle was, however, one of many in what both sides had termed a war of attrition.
France and the Balkans weren't the only battlegrounds in World War I. The Ottoman Empire's entry into the war prompted British forces to also concentrate on Turkey. In February 1915, British forces bombed Turkish forts in the Dardanelles. Two months later, on April 25, Allied troops, mainly Australians and New Zealanders (ANZACs), landed at Gallipoli, in an attempt to seize the strategic peninsula. The result was a decisive victory for the Ottoman Empire. British troops (along with the ANZACs) eventually evacuated the area entirely.
Also in the southern European front, Italy joined the war, in 1915, on the side of the Allies, spurning the Triple Alliance entirely. As was the case with the Western Front, Italian troops attacked Austria-Hungary in many waves but gained little ground. Romania also entered the war on the side of the Allies, and fighting took place in some areas that had been hotspots during the Crimean War 60 years before.
The Great War also saw the advent of aerial warfare, as the new invention of the manned airplane was turned to military use with devastating force. Each side produced thousands of planes, which performed many actions during the war, including reconnaissance, bombing of targets, and even escort of ships. "Dogfights" between fighter pilots have gained the stuff of legend.
Political upheavals in Russia intensified during the war, and the Russian Revolution overthrew the tsar in 1917. Russia then took itself out of the war. Germany and Russia signed an armistice in December 1917 and then the Treaty of Brest-Litovsk on March 3, 1918.
Germany in early 1917 had begun a policy of sinking ships of all countries, not just ones with which it was at war. German U-Boats (submarines) soon sank American ships.
In addition, the publication of the Zimmerman Telegram helped sway American public opinion in favor of war against Germany. Arthur Zimmermann, the German foreign minister, had tried to convince Mexico to attack the United States, in an effort to retake Arizona, New Mexico, and Texas, all territories that changed hands at the end of the Mexican-American War. British intelligence agents found out what was in the telegram and gave the information to the U.S. Government, which told the world.
These things prompted the United States to end its neutrality and enter the war on April 6, 1917, on the side of the Allies. American troops landed in Europe soon thereafter. The American army was small at first, but the Selective Service Act paved the way for the draft, and nearly 3 million men joined the American Expeditionary Forces, which provided the Allies with a much-needed boost in morale and manpower. At one point, American troops were shipping out to Europe at the rate of 10,000 a day. Germany had no such reserves to draw from.
Without a Russian army to fight, Germany was able to find some new success on the Western Front in early 1918. However, this success was short-lived. The war dragged on for several more months, and Germany requested an armistice in October 1918. Peace was declared on November 11. The final war-ending settlement, the Treaty of Versailles, was signed on June 28, 1919.