In what is now known as the July Crisis, the simultaneous Thucydidean dynamics between London and Berlin, and between Berlin and Moscow, became interlocked. Germany’s determination to prop up its ally and forestall the menace of a rising Russia led to its declaration of war against the tsar — and his ally, France. The German general staff’s war plan for a quick defeat of France called for invasions of Luxembourg and Belgium. But by invading Belgium on the way to crushing France, Germany crossed a red line for Britain.
