King Gustav III was the King of Sweden from 1771 until his assassination in 1792. He is known for his efforts to modernize Sweden, promoting arts and culture, and establishing the Royal Swedish Opera. His reign is often associated with the Enlightenment, as he sought to implement reforms in government and society. Gustav III also played a significant role in European politics, engaging in wars against Russia and Denmark. His reign was marked by a struggle between royal authority and parliamentary power, leading to tensions that ultimately contributed to his downfall.