Imperialism, militarism, nationalism, and alliance systems contributed to tensions between European powers and caused World War I. Imperial nations sought resources and territory, leading to conflicts over control of areas like the Balkan Peninsula and access to the Mediterranean Sea. An arms race and development of powerful navies through militarism heightened tensions. Extreme nationalism made countries view themselves as superior to others. Finally, the system of alliances that formed two teams - the Triple Entente and Central Powers - pulled more countries into war when the assassination of Archduke Franz Ferdinand ignited conflict between Austria and Serbia.