The First World War (WWI) was fought from 1914 to 1918 and the Second World War (or WWII) was fought from 1939 to 1945. They were the largest military conflicts in human history. Both wars involved military alliances between different groups of countries.

World War I (a.k.a the First World War, the Great War, the War To End All Wars) was centered on Europe. The world warring nations were divided into two groups namely ‘The Central Powers’ and ‘The Allied Powers’. The central powers group consisted of Germany, Austria-Hungary, Turkey and Bulgaria. The Allied powers group consisted of France, Britain, Russia, Italy, Japan, and (from 1917) the U.S.

World War II (a.k.a the Second World War), the opposing alliances are now referred to as ‘The Axis’ and ‘The Allies’. The Axis group consisted of Germany, Italy, and Japan. The Allies group consisted of France, Britain, the U.S., the Soviet Union, and China. World War II was especially heinous because of the genocide of Jewish people perpetrated by the Nazis.

Comparison chart

World War I versus World War II comparison chart
World War IWorld War II
Period and duration 1914 to 1918; 4 years 1939 to 1945; 6 Years
Triggers and causes Assassination of Archduke Francis Ferdinand of Austria in June 1914. Militarism, Imperialism, nationalism and alliance system. Political and economic instability in Germany. The harsh conditions of the Treaty of Versailles Rise of power of Adolf Hitler and his alliance with Italy and Japan to oppose the Soviet Union
Conflict between The Central Powers (Germany, Austria-Hungary, and Turkey) and the Allied Powers (France, Britain, Russia, Italy, Japan, and (from 1917) the U.S.) The Axis Powers (Germany, Italy, and Japan) and the Allied Powers (France, Britain, the U.S., the Soviet Union, and China)
Casualties Estimated to be 10 million military dead, 7 million civilian deaths, 21 million wounded, and 7.7 million missing or imprisoned. Over 60 million people died in World War II. Estimated deaths range from 50-80 million. 38 to 55 million civilians were killed, including 13 to 20 million from war-related disease and famine.
Genocide The Ottoman Empire (Turkey) carried out genocide of Armenians. German Nazis committed genocide against Jews and Romanis, people with disabilities, Poles, homosexuals, Jehovah's witnesses and Afro-Germans.
Methods of warfare Fought from lines of trenches and supported by artillery and machine guns, infantry assault, tanks, early airplanes and poisonous gas. Mostly static in nature, mobility was minimal. Nuclear power and missiles were used, modern concepts of covert and special operations. Submarines and tanks were also more heavily used. Encryption codes for secret communication became more complex. Germany used the Blitzkrieg fighting method.
Outcomes The German, Russian, Austro-Hungarian and Ottoman empires were defeated. Austro-Hungarian and Ottoman empires ceased to exist. The League of Nations was formed in the hope of preventing another such conflict. The war ended with the total victory of the Allies over Germany and Japan in 1945. The Soviet Union and the United States emerged as rival superpowers. The United Nations was established to foster international cooperation and prevent conflicts.
Post-war politics Resentment with the onerous terms of the Treaty of Versailles fueled the rise of Adolf Hitler's party in Germany. So in a way, World War I led to World War II. The first Red Scare in the U.S. to fight communism. There was a Cold War between the United States and Russia after the end of the Second World War until the collapse of the USSR (1947-1991). The wars in Afghanistan, Vietnam and Korea were, in a sense, proxy wars between the two nations.
Nature of war War between countries for acquiring colonies or territory or resources. War of ideologies, such as Fascism and Communism.
Abbreviation WWI or WW1 WWII or WW2
Also known as The Great War, The World War, The Kaiser's War, The War of the Nations, The War in Europe, or The European War, World War one, First World War, The war to end all wars Second World War, World War Two, The Great Patriotic War
American president during the war Woodrow Wilson FDR, Harry Truman
British Prime Minister during the war H. H. Asquith (1908-1916); David Lloyd George (1916-1922) Winston Churchill
Predecessor Napoleonic Wars World War I
Successor World War II Cold War

Causes of the War

World War I Trigger

This video from Yale explains the events that led to World War I:

Causes of World War II

The Versailles Treaty signed at the end of World War I not only lay the moral blame of the conflict on Germany but also forced the Germans to make huge payments to the victors of the war. France and Britain needed these reparations payments in order to pay down their own debts. But they were highly onerous, arguably unjustifiably so, and were deeply unpopular in Germany. Hitler seized on this growing resentment and promised to "undo this injustice and tear up this treaty and restore Germany to its old greatness". In fact, the payments demanded were so large that Germany was able to repay the final installment of interest on this debt only on October 3, 2010.[1] The following causes of World War II are generally acknowledged:

The following documentary delves into the causes of World War II:

Sequence of events

World War I

The sequence of events for World War I began in 1914 with Austria-Hungary declaring war on Serbia on 28 July 1914 in a bid to reassert its authority as a Balkan power. With war breaking out between Austria-Hungary on one side and Serbia on the other, Europe quickly fell back to the alliances nations had formed. Austria-Hungary and Germany were allies. Serbia was allied with Russia; as was France. Russia aided Serbia and attacked Austria. So Austria-Hungary was fighting in two fronts with Serbia and with Russia and consequently lost on both fronts. In a bid to aid Austria-Hungary against Russia, and fearing an attack from France, Germany mobilized its army and attacked France.





1919 A formal state of war between the two sides persisted for another seven months, until signing of the Treaty of Versailles with Germany on 28 June 1919

World War II

The war that broke out in 1939 was a war for the European balance of power. The immediate cause of the conflict was the German demand for the return of Danzig and part of the Polish ‘corridor’ granted to Poland from German territory in the Versailles Treaty of 1919. Poland refused to agree to German demands, and on 1 September 1939 overwhelming German forces launched the Polish campaign and defeated her in three weeks. Russia also invaded eastern Poland. Poland thus got divided into two parts. In March 1939 Britain and France had guaranteed Polish sovereignty, and in honor of that pledge first demanded that German forces withdraw, and then on 3 September declared war on Germany. America was committed by the Neutrality Acts of 1935 and 1937 of non-intervention in overseas conflicts.

This video presents a concise history of the events of World War II:




A montage of World War II photos
A montage of World War II photos


The entry of the USA signaled a change in the political balance of the war of great significance. German forces in Stalingrad surrendered in January 1943and by May 1943 Italian and German forces finally surrendered in Tunisia, enabling the Allies to mount the invasion of Sicily and then Italy. Italy sued for an armistice in September 1943.


American economic might and political interests helped to bind together the different fronts of conflict, while America's worldwide system of supply and logistics provided the sinews of war necessary to complete the defeat of the aggressor states. A major intelligence deception operation and declining air power weakened the German response and by September 1944 German forces had been driven from France.


War strategies

Many of the weapons that dominate military operations today were developed during World War I, including the machine gun, the tank and specialized combat aircraft. This is a great video that explains the military strategies and tactics used during World War I.


World War I

World War II


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