Beginning as a religious and dynastic conflict in the Holy Roman Empire, the Thirty Years' War drew in most major European powers and devastated much of central Europe through battle, siege, famine and disease. Some regions of the German lands are estimated to have lost a third or more of their population, with many towns sacked or depopulated. The war drove rulers to invest in bastioned fortifications and standing armies. It ended with the Peace of Westphalia in 1648.
The Westphalian settlement entrenched the sovereign territorial state, and the war's destruction and fortress-building shaped a century of defensive, absolutist urbanism across Europe.