- Paris, France: The French government submits to the British strength in Fashoda and pulls out, signalling to the end of the colonial Fashoda War.
- Port Arthur, Japan: 8 February – The Imperial Navy attacks the Russian Eastern Fleet in Port Arthur, igniting the Russo-Japanese War.
- London, United Kingdom: 27 February – The United Kingdom honors its alliance with Japan and sends the Royal Navy to aid the Japanese.
- Afghanistan and British India: March – The British commence an offensive through Afghanistan into the Turkic regions of Russia.
- Southampton, United Kingdom: 12 November – Russia signs the Treaty of Southampton with Japan and the United Kingdom; ceding all of Sakhalin and the Kuril Islands to Japan and ending the Russo-Japanese War.
- Sarajevo, Austria-Hungary: 28 June – Archduke Franz Ferdinand is assassinated by Serbian nationalists while traveling in the city with his wife. The July Crisis begins.
- Austria-Hungary: 28 July – The Austro-Hungarian Empire declares war on Serbia after a month since the assassination of Franz Ferdinand. Russia honors the alliance with Serbia and declares war on Austria-Hungary; marking the beginning of the Continental War.
- Berlin, Germany: 1 August – Germany declares war on Russia and enters the Continental War in favor of the Austro-Hungarians.
- France and Belgium: 4 August – Anticipating a German offensive, France launches an invasion of Belgium to strike first at the Germans.
- United Kingdom: 5 August – The United Kingdom breaks its alliance with Belgium to avoid being entangled in continental affairs in Europe, however grants Germany permission to sends its troops through Belgium.
- France: 20 December – German forces successfully crush the French Army at the Battle of Verdun.
- Paris, France: 29 December – With the German Army nearing Paris, France ultimately offers peace terms with the German Empire.
- Germany and Russia: 30 December – Germany launches the Baltic Offensive into Russia.
- Petrograd, Russia: 12 January – Following France, Russia sues for peace with Germany. The Continental War draws to a close.
- New York City, United States: 1 March – In fears of German militarism, the Anglo-American alliance is signed between U.S. President Charles E. Hughes and British Prime Minister David Lloyd George.
- France: 10 May – National Party candidate Pierre Taittinger is inaugurated as the French president. Known for being staunchly revanchist, he won overwhelmingly won the elections by a large margin.
- Ukraine: 1 November – The Russian Republic decides to invade Ukraine, nearly dragging itself into conflict with Germany.
- Petrograd, Russia: 9 November – Russian President Alexander Kerensky signs the Petrograd Agreement with German Chancellor Franz von Papen, guaranteeing Ukraine for Russia.
- Hohenzollern Castle, Germany: 4 June – Wilhelm II, the longest reigning German monarch in history, dies at Hohenzollern Castle. His son, Crown Prince Wilhelm, succeeds him as Wilhelm III.
- France and the Benelux: 20 September – The Great War begins with the Battle of the Benelux, intended to occupy Belgium, the Netherlands, and Luxembourg.
- Berlin, Germany: 21 September – German Chancellor Franz von Papen, seeing the Invasion of the Benelux as a violation of the previous Moscow Agreement, honors its alliance with Belgium and declares war on France.
- Finland and Russia: 22 September – Hoping to strike at the German client states while they are busy fighting France, Russia launches an invasion of Finland to retake lands formerly held by Russia.
- Vienna, Austria-Hungary: 30 September – With another war beginning in Europe, Austria-Hungary allies with Germany and declares war on France and Russia.
- The Benelux: 8 October – With the German Army ill-prepared to combat France, along with a majority of Belgian and Dutch troops being outnumbered by the French Army, Belgium and the Netherlands surrender to France.
- French-occupied Benelux: 3 January – France launches the Rhine Offensive into Germany, hoping to gain control of the heavily-industrialized Ruhr region.
- London, United Kingdom: 15 January – After the sinking of the HMS Prince of Wales off the coast of the Channel Islands, along with other previous incidents between British and French naval vessels, the United Kingdom declares war on the Entente.
- Königsberg, Germany: 22 February – German forces are defeated at the Battle of Königsberg against the invading Russian forces. East Prussia falls to the Russians.
- West Prussia, Germany: 1 March – Under the command of General Anton Denikin, the Russian Army begins working its way to Danzig. German Field Marshall (xx) retreats from West Prussia into Danzig, expecting the Russian attack.
- German Central Africa: 16 September – The Kaiser Bomb I becomes the first successful atomic bomb in history after the works of Albert Einstein. The Western Allies begin their own nuclear programs to compete with Germany after the war.
- Vienna, Austria-Hungary: 1 June – The Treaty of Independence is signed, officially granting Hungary independence from the Austro-Hungarian Empire. The Austrian Empire is recognized as the successor state to Austria-Hungary.
- Vienna, Austria: 12 September – The Bohemian independence referedum falls in favor of Bohemia, resulting in Austria granting independence to the Bohemians.