Responsibility for Outbreak: Germany, specifically the German Empire under leaders like Kaiser Wilhelm II, was perceived as bearing much of the responsibility for instigating the First World War. The July Crisis of 1914, culminating in the assassination of Archduke Franz Ferdinand of Austria, revealed a complex system of alliances that tied European nations together. Germany's support for Austria-Hungary after the assassination was viewed as provocative and aggressive.
Austria-Hungary and Serbia were the main adversaries, but diplomatic blunders, including an ultimatum Austria-Hungary issued to Serbia with German backing, led to a chain of events that resulted in declarations of war. Germany's role in escalating tensions contributed to the view that they should be held accountable for the disastrous consequences.
Damage and Casualties: Germany's invasion of Belgium, as well as their military tactics on the Western Front, such as unrestricted submarine warfare (U-boat campaign), left widespread destruction and significant loss of human life. Civilian populations faced enormous hardships during the war, exacerbating public outrage and the demand for reparations to restore what was lost.
Territorial Adjustments: Territorial disputes and border modifications aimed to adjust Europe's geopolitical landscape post-war. This involved taking into account both military and ethnic factors. Certain provisions for ceding German territories as part of peace agreements were contentious but considered essential to ensure balance of power in the region.
Military Limitations: To reduce Germany's potential for future aggression, limitations on Germany's military size, production capabilities, and military activities, such as prohibitions on maintaining air forces or large standing armies, were imposed.
It's essential to consider other viewpoints and factors beyond those provided and to acknowledge that there are differing historical interpretations and nuances to these reasons.