World War I

Between 1912 and 1913, the Balkan nations of Bulgaria, Serbia, Greece, and Montenegro fought two back-to-back wars that dramatically redrew the map of southeastern Europe. In the First Balkan War (1912–13), they attacked the declining Ottoman Empire and rapidly seized almost all its remaining European territory, including the fortress city of Adrianople (modern Edirne, Turkey). A Second Balkan War (1913) broke out immediately as the victors fought each other over the spoils. The wars displaced hundreds of thousands of people and intensified nationalist hatreds — particularly between Serbia and Austria-Hungary — directly creating the conditions that led to the assassination of Archduke Franz Ferdinand in Sarajevo in 1914 and the outbreak of World War I.

This moment unfolded near Ypres, in Belgium — a small, low-lying country squeezed between France to the south and west, Germany to the east, and the North Sea to the north, exactly the kind of flat, open terrain that made it a brutal battleground. On Christmas Eve and Christmas Day 1914, German and Allied soldiers along sections of the Western Front spontaneously stopped shooting, crossed into no man's land, exchanged greetings, and in some places played football together — one of the most extraordinary informal truces in military history. Belgium sits at a geographic crossroads where the North European Plain funnels movement between the great powers of France and Germany, which is precisely why its soil has soaked up so many of Europe's wars across the centuries. Smaller than the state of Maryland but bordered by three major powers, Belgium's flat, open landscape offers almost no natural defensive barriers — rivers and ridgelines are shallow and short, leaving armies to fight over every muddy field.

This is Sarajevo, the capital of modern Bosnia and Herzegovina — a city nestled in a mountain-ringed valley along the Miljacka River, deep in the Balkan Peninsula where Central Europe grades into the southeastern corner of the continent. On June 28, 1914, Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, was shot and killed by Gavrilo Princip, a Bosnian-Serb nationalist tied to the Black Hand secret society — a single act that triggered the July Crisis and pulled every major European power into war within six weeks. The Balkans sit at the crossroads where the European continent narrows toward the Aegean and Black Seas, a region where Slavic, Ottoman, and Habsburg empires overlapped for centuries, making it one of history's most contested cultural and political fault lines. That geographic pressure-cooker quality — mountains carving up territory, rival powers pressing in from every direction — helps explain why this compact peninsula produced so many flashpoints in the modern era.

This was the Gallipoli Peninsula in Turkey, jutting into the Aegean Sea at the point where the Dardanelles strait — the narrow waterway dividing Europe from Asia — connects to the Sea of Marmara. In 1915, Allied forces launched a major amphibious assault here during the First World War, attempting to seize the strait and open a route to the Ottoman capital; the campaign lasted months, cost hundreds of thousands of casualties on both sides, and ultimately failed. The Dardanelles is one of the world's most strategically important waterways — only about 1.2 kilometres wide at its narrowest — because it controls the only sea passage between the Black Sea and the Mediterranean, making whoever holds it enormously powerful over trade and naval movement. Turkey sits at the crossroads of two continents, and the Gallipoli Peninsula is one of the most vivid places on Earth where that Europe-Asia divide becomes a physical, visible line of water.

This naval battle took place in the North Sea off the Jutland Peninsula, the finger of land that extends northward from continental Europe toward Norway and Sweden, separating the North Sea from the Baltic. Fought over two days in 1916, the Battle of Jutland was the largest naval engagement of World War I, pitting the British Royal Navy's Grand Fleet against the German Imperial Navy's High Seas Fleet; Germany sank more ships and killed more sailors, yet the German fleet retreated and never seriously challenged British naval dominance again. The North Sea is a relatively shallow body of water — rarely deeper than 200 metres — sitting on the continental shelf between Britain and northwestern Europe, making it one of the world's most strategically contested stretches of ocean for centuries. Controlling it meant controlling access between the Atlantic and the Baltic, which is exactly why both sides fought so hard here.

This was Verdun, a fortified city on the Meuse River in northeastern France — sitting in the rolling hills of the Western European interior, roughly midway between the Rhine to the east and the English Channel coast to the northwest. In 1916, two industrial armies fought here for nearly ten months in one of World War I's longest and deadliest battles, with around 700,000 soldiers killed or wounded on both sides, as artillery, poison gas, and machine guns turned the landscape into a wasteland of craters and mud. Verdun sits in the Lorraine region, a historically contested borderland between France and Germany — the kind of flat, river-crossed terrain that armies have fought over for centuries because it offers no natural wall to stop an advance. That lack of a strong geographic barrier between France and its eastern neighbours made this corridor one of the most fought-over strips of land in all of European history.

Washington, D.C., the capital of the United States, sits on the Atlantic seaboard of North America, roughly midway along the eastern coast between the Canadian border and the Gulf of Mexico — the destination where this intercepted message caused an uproar. In January 1917, German Foreign Secretary Arthur Zimmermann sent a secret telegram to Mexico proposing a military alliance against the United States; British intelligence intercepted it, and when its contents were made public, the resulting outrage helped push the U.S. Congress to declare war on Germany. Washington, D.C. occupies a low, flat position on the Potomac River, chosen deliberately on the border between northern and southern states as a political compromise when the young nation needed a neutral federal capital. The Atlantic coast here connects via ocean routes to both Europe and the Caribbean, making it a natural hub for the transatlantic communications and diplomacy that defined this era of world war.

This is Petrograd — now called Saint Petersburg — in Russia, sitting at the eastern tip of the Baltic Sea where the Neva River meets the Gulf of Finland, exactly where Europe's great northern plain transitions into the Eurasian heartland. In October 1917, Lenin's Bolshevik Party overthrew Russia's Provisional Government, seizing control of the city and establishing the foundation of a Soviet state — one of the most consequential political upheavals of the modern era. Saint Petersburg sits at roughly 60 degrees north latitude, on the same latitude as southern Alaska, making it one of the world's largest cities in such a cold, high-latitude position. The city was built by Peter the Great on marshy delta islands where the Neva meets the Baltic, giving Russia its long-sought warm-water access to European sea trade — a geographic ambition that shaped Russian expansion for centuries.

Camp Funston sits in Kansas, deep in the interior of the United States — on the broad, flat Great Plains that stretch from the Gulf of Mexico northward toward Canada, far from any ocean coast. It was here, in 1918, that one of the earliest known outbreaks of the influenza pandemic later called the 'Spanish Flu' was recorded; the disease ultimately infected an estimated 500 million people worldwide and killed between 50 and 100 million, more than the entire First World War. Kansas lies near the geographic center of North America, sitting on the vast interior lowland basin between the Rocky Mountains to the west and the Appalachians to the east. This central position, connected to military movement networks spreading in every direction, made it a chilling starting point for a disease that would circle the entire globe.

The signing took place in Brest-Litovsk, a city now called Brest in modern Belarus, sitting on the flat lowland plain where the Bug River marks the boundary between Eastern and Central Europe, roughly midway between the Baltic and Black Seas. On March 3, 1918, Soviet Russia signed a treaty with the Central Powers here, ending its involvement in World War I at enormous cost — surrendering vast territories including Ukraine, Finland, and the Baltic states, stripping away roughly a third of European Russia's population and farmland. Brest sits at a geographic crossroads that has made it strategically fought over for centuries: it lies on the natural invasion corridor across the North European Plain, the same flat, open lowland highway that armies have used to march between Western Europe and Russia for hundreds of years. That absence of mountain barriers across this plain is one of the defining geographic facts of European military history.

This offensive launched from near Saint-Quentin, a town in northern France — sitting on the flat plains of Picardy, roughly midway between the English Channel coast and the Belgian border, west of the Rhine and east of Paris. In spring 1918, German forces launched Operation Michael, a massive assault from their established Hindenburg Line positions, driving westward in an attempt to shatter the Allied front before American reinforcements could tip the balance. The Picardy plain offered little natural cover — no mountains, no wide rivers to anchor a defence — which is partly why this stretch of northern France became one of the most fought-over corridors in the entire war. The region sits on a broad, gently rolling chalk plateau that connects the Paris Basin to the Belgian lowlands, making it a natural invasion corridor that armies have used for centuries.

Paris, France — sitting on a wide bend of the Seine River in the heart of Western Europe, exactly where the flat North European Plain rolls toward the Atlantic coast — was where Allied leaders convened in 1919 to reshape the world after World War I. Representatives of four major Allied powers held the Paris Peace Conference, producing a series of treaties that redrew national borders across Europe, the Middle East, and beyond, dismantling defeated empires and creating new states. Paris sits at the geographic core of Western Europe, roughly equidistant between the English Channel to the north and the Mediterranean coast to the south, which has made it a natural hub for continental diplomacy for centuries. The Seine, flowing northwest through the city before emptying into the English Channel near Normandy, connected Paris to Atlantic trade routes and helped it grow into one of Europe's great political and cultural capitals.

On 28 June 1919 — exactly five years after the assassination of Archduke Franz Ferdinand — Germany and the Allied powers signed the Treaty of Versailles in the Hall of Mirrors at the Palace of Versailles, France. Germany was forced to accept sole responsibility for the war, pay enormous reparations, surrender territory to neighbouring countries, and reduce its army to just 100,000 men. Germany lost about 13% of its territory and 10% of its population. The humiliation and economic hardship caused by the treaty created widespread resentment that Adolf Hitler later exploited, contributing directly to the rise of Nazism and the outbreak of World War II just twenty years later.