World War I was a major conflict that took place between 1914 and 1918. It involved all of the world's great powers. They were divided into two opposing alliances: the Allies, consisting of France, Russia, Britain, and later Italy, and the Central Powers, which included Germany, Austria-Hungary, Bulgaria, and later Turkey. When a Serbian nationalist assassinated Archduke Franz Ferdinand of Austria-Hungary in Sarajevo on June 28, 1914, the war officially started. This event triggered a series of diplomatic crises, leading to declarations of war by both sides.
The course of World War I saw dramatic changes over its four-year span. New technologies, such as machine guns, tanks, submarines, and airplanes, were introduced for use in battle for the first time ever. These advances changed how battles were fought. Static defensive positions evolved into more fluid mobile strategies with rapid advances or retreats, depending on who had control at any given moment. In addition to this shift in tactics, there also arose a number of new methods used to fund wars, including taxation increases throughout Europe as well as large loans taken out from American banks, which helped sustain the fighting until its conclusion in November 1918 with Germany's surrender.
World War I is considered one of history's most destructive conflicts, with millions dead due to trench warfare along various fronts, like those found in Western Europe or the Gallipoli Peninsula. The Allied forces attempted to break through Ottoman lines held up against them since 1915. In addition to these devastating losses, there were even more fatalities caused indirectly by food shortages resulting from naval blockades imposed across many parts of Europe. Economic ruin spread throughout much of the continent, resulting in massive poverty levels seen in the post-World War I era amongst citizens everywhere. People were unable to cope without aid sent their way to help rebuild what had once been so prosperous just years prior.
Not only did physical destruction occur, but psychological damage followed the soldiers home too, leaving many men struggling to deal with PTSD symptoms long after an armistice agreement was signed. This armistice made sure they'd never have to face horrors on the battlefield again. Finally, the political repercussions stemming from this global conflict proved to be extremely influential. They formed opinions among leaders and states around the world concerning foreign relations. Actions taken towards enemies created a lasting legacy that continues to shape international affairs to this day, despite the passing century since the Great War concluded.