What were some of the causes of World War 1?
Technology, Nationalism and very large conscript Armies combined with an aging system of Government and Global Economy to create a War, the scale and intensity that had not been experienced before.
Weapons Technology, Railways, Communications Systems, Food Production and Preservation, Logistics, Medicine, Industrial Revolution and Science all received an incredible boost over the previous 100 years.
Nationalism was a powerful human motivating force that Revolution, the Napoleonic Wars and their aftermath had forged in Europe.
Conscript armies mobilized masses of men, motivated by Nationalism, to run the new machinery of war.
The system of government, of Monarchy and Empire in Europe, lacked necessary restraint to stop or slow the momentum to War. Once the War started, it could not stop the escalation. When the War had progressed beyond all reason they could not and would not bring it to an end. The Class System made dialogue between master and men difficult. Common people were expected to to "get on with it" without question or complaint.
The concentration of global wealth and resources that Colonialism and Empire had placed at the disposal of Europe meant that an intense war could be sustained for a very long time.