The First World War was fought from 1914 to 1918. Its causes are discussed below.

i) Imperialistic Conflicts: 

When the imperialist powers entered into mutual competition to conquer the world, conflicts among them became widespread. The international problems surfaced during this period caused mutual mistrust and enmity. The conflicts among imperialist powers led to the war.

ii) Military Alliances: 

The competition among the imperialist powers drove them to sign military alliances. The Tripple Alliance was formed by Germany, Italy and Austria-Hungary. To counter this, Britain, France and Russia formed the Triple Entente. The formation of such alliances created an atmosphere of war in Europe.

iii) Aggressive Nationalism: 

Aggressive nationalism was one of the strategies adopted by the imperialist countries to succeed in their competitions. The European nations used aggressive nationalism to invade other countries. Aggressive nationalists considered their own nations as the supreme and justified whatever be the actions of their nations. The Pan Slav Movement under Russia, the Pan German Movement under Germany and the Revenge Movement in France were examples for aggressive nationalism.

iv) International crises: 

Imperialist rivalries drove the European countries into several crises. Some of them were Moroccan crisis and Balkan crisis.

Moroccan crisis: 

A secret treaty was signed between Britain and France in 1904. According to this, Britain recognised the claim of France over Morocco. The French claim over Morocco was opposed by Germany and she sent battleships to Moroccan port Agadir. This was the Moroccan crisis. France agreed to transfer a part of French Congo to Germany and Germany agreed to concede Morocco to France in return.

Balkan crisis: 

The Balkan region is situated in Europe, close to the Aegean Sea and the Black Sea. It was a part of the Ottoman Empire. In 1912, the Balkan League (Greece, Bulgaria, Serbia and Montenegro) defeated Turkey. However, the conflict among the allied nations in sharing the benefits of the war led to the break up of the League and resulted in wars among them.

Immediate cause: 

The assassination of Archduke Francis Ferdinand, the heir to the throne of Austria by Princep, a Serbian youth at the Bosnian capital Sarajevo in June 1914 was the immediate cause. Austria held Serbia responsible for it and declared war pESerbia on 28 July 1914. Almost all the nations of the world directly or indirectly were involved in it.

Results

• Over 10 million people lost their lives or were injured in war. 
• Liberation movements in Asia and Africa strengthened. 
• Economic dominance of Europe diminished. 
• Agriculture, industry and communication systems were destroyed. 
• Poverty, unemployment and inflation increased. 
• In a bid to bring peace in the world, the League of Nations was formed. 
• Emergence of Fascism and Nazism.