於1914年爆發於歐洲的大戰，引爆點就在昨天波赫的首都塞拉耶佛。由英國、法國、俄羅斯帝國組成的協約國，對上德意志帝國、奧匈帝國、義大利王國組成的同盟國。後來戰線延伸到日本、美國，甚至是拉丁美洲（名義上參戰），所以又被稱為世界大戰（二戰爆發後才回頭加上「第一次」）。根據統計，這場戰爭總共有6,500萬人參戰，超過1,600萬人喪生。
一次世界大戰造成歐洲衰退，四大帝國解體（奧匈帝國、俄羅斯帝國、德意志帝國、鄂圖曼土耳其帝國）， 美國和日本則趁勢崛起。戰後簽署的《凡爾賽條約》對戰敗國德國實施極為苛刻的賠款和軍事制裁，埋下德國民眾強烈的民族復仇主義種子，最終在希特勒的煽動下爆發規模空前的二次世界大戰。

Date: 1914 – 1918

The Great War broke out in Europe in 1914 and the tipping point happened to be Sarajevo, the capital of B&H, the country featured yesterday. Britain, France, and the Russian Empire formed the Entente Powers fighting against the Central Powers of Germany, Austria-Hungary and the Kingdom of Italy. Later, the front line extended to Japan, the United States, and even Latin America (nominally) and hence the conflict was named the World War (After WWII broke out, “first” was added retrospectively). According to statistics, a total of 65 million people participated in the war and more than 16 million people lost their lives. 

World War I led to the decline of European powers and the disintegration of the four empires (Austro-Hungarian Empire, Russian Empire, German Empire, and Ottoman Turk Empire), while the United States and Japan took advantage and became the new powers. The Versailles Treaty signed after the war imposed extremely harsh reparations and military sanctions on Germany, planting a seed of strong national revanchism among the German population. Eventually, fueled by Adolf Hitler, WWII, a conflict of unprecedented scale, broke out.