Before WWI, nations strengthened their armies and navies to protect their interests. If one nation increased its military strength, its rivals felt threatened and built up their own military in
response. This created an atmosphere of _ in the 1900s.

On 28 June 1914, Archduke Franz Ferdinand, the heir to the Austro-Hungarian throne, and his wife were assassinated by a Serbian-backed terrorist. During the crisis that followed, Europe's leaders made a series of political, diplomatic and military decisions that would turn a localised conflict in south-east Europe into a global war.

Austria-Hungary, with German encouragement, declared war on Serbia on 28 July. Russia's support of Serbia brought France into the conflict. Germany declared war on Russia on 1 August and France on 3 August. Germany's violation of Belgian neutrality and British fears of German domination in Europe brought Britain and its empire into the war on 4 August.

These actions reflect the fears, anxieties and ambitions of the European powers. The decisions for war were made in the context of growing nationalism, increased militarism, imperial rivalry and competition for power and influence. Europe's leaders were willing to go to war to defend or extend national interests and their choices were shaped by a combination of long and short-term foreign policy goals, political pressures at home, previous crises, and the system of opposing alliances that had developed over the previous 35 years.

Explanation:

And I'm 6th grade and you need help with that I know that by heart.

to extend a country’s power and influence

the main objectives of the progressive movement were eliminating problems caused by industrialization, urbanization, immigration, and political corruption.