Leopold I was Holy Roman emperor during whose lengthy reign Austria emerged from a series of struggles to become a great European power.
When his elder brother, Ferdinand IV, died quite unexpectedly, Leopold suddenly found himself heir apparent to the Austrian Habsburg lands. The next year he was elected and crowned king of Hungary. He was elected and crowned Holy Roman emperor in 1658 and married into the Spanish throne in 1666. After struggles with the Turks and the French, Austria emerged under Leopold as a great European power.