World War I

The 28th of July, 1914, marked the start of World War I, often known as the First World War, and the 11th of November, 1918, marked the conclusion of the conflict. In what was referred to as the "Great War" by its contemporaries, several countries of Europe, Russia, the United States, and the Ottoman Empire were involved, as well as sections of Africa and Asia. 9 million people were killed in war, while an estimated 5 million civilians perished as a result of occupied territories, bombings, famine and illness. The 1918 influenza pandemic, which was aggravated by the mobility of soldiers throughout the war, contributed to millions of extra fatalities in the Ottoman Empire.

The Triple Entente of France, Russia, and Britain; and the Triple Alliance of Germany, Austria-Hungary, and Italy were the two major European powers by 1914. After Gavrilo Princip, a Bosnian Serb, assassinated Archduke Franz Ferdinand, the Austro-Hungarian heir, on June 28, 1914, tensions in the Balkans reached a boiling point. Austria-Hungary blamed Serbia for the July Crisis, a failed diplomatic effort to prevent war. After Austria-Hungary declared war on Serbia on July 28th, Russia stepped in to defend the country, and by August 4th, the alliance system had drawn in Germany, France, and Britain, as well as their respective colonies. The Central Powers were created in November 1914 by the Ottoman Empire, Germany, and Austria-Hungary, while the Allies were founded in April 1915 by the United Kingdom, France, Russia, and Serbia.

Germany's goal in 1914 was to destroy France first and then move its troops to Eastern Europe and defeat Russia in the Schlieffen Plan, which was dubbed "The Great Plan." It was only at the end of 1914 that the two sides confronted one other along what would become known as "the Great Western Front," a continuous chain of trench lines running from the English Channel to Switzerland. Eastern Front battles were more fluid because Russia and Austria-Hungary were constantly adding and subtracting vast chunks of land. Aside from these three major theatres: the Middle East, Italy, and the Balkans, the war brought Bulgaria, Romania and Greece into conflict.

Early in 1915, Russia had suffered a string of humbling defeats in the Tannenberg and Masurian Lakes twin battles. As a result of the several engagements, the Russians' army had been decimated, and the Germans had sent a large portion of their forces to the Eastern Front. Despite the Russians' victory in the siege of Przemyl, the Germans began preparing to take Galicia by April of that year. The Gorlice–Tarnów assault was initiated by the Germans in May, which finally led to a Russian retreat. Warsaw had been taken over by the Germans on August 5th. In September 1915, the conflict was finally over, and Poland and portions of Minsk had been taken.