A 1812 treaty forced Prussia to help Napoleon invade the Russian Empire
Napoleon Bonaparte used his immense influence in 1812 to pressure Prussia into a reluctant military alliance, forcing them to provide thousands of troops for his ill-fated invasion of Russia.
In 1812, King Frederick William III of Prussia was forced to sign the Treaty of Paris, a defensive and offensive alliance with Napoleon's France. Having been soundly defeated by the French years earlier, Prussia had little choice but to agree to Napoleon's demands or face total annexation.