Germany and Austria-Hungary bear the greatest share of blame

Hastings takes a clear position in a long-running historical debate over who caused the First World War, arguing the evidence points overwhelmingly toward German and Austro-Hungarian leadership as the primary instigators, rather than treating the war as an accidental tragedy for which no one bears particular responsibility. He builds this case through close reading of the July Crisis, showing how Austria-Hungary's determination to punish Serbia after the assassination of Archduke Franz Ferdinand received deliberate encouragement from Berlin's military leadership, who calculated that a localized war served German interests even at serious risk of wider conflict.

Hastings acknowledges rival schools of thought, including historians who assign greater blame to Russian mobilization or argue Britain should have stayed neutral, treating these seriously rather than dismissing them outright. Ultimately, though, he judges German strategic calculation and Austrian vindictiveness as the decisive ingredients that turned a containable Balkan crisis into a general European war.

Takeaway: Hastings insists the war wasn't simply everyone's fault equally — some governments made choices in July 1914 that specifically, and knowingly, risked catastrophe.