For centuries Italy had been a collection of several countries, each with their own ruler. In the 1850s there was a lot of political unrest in the country. Verdi often wrote music for large choruses in his operas. The words of these choruses were often about fighting for freedom, and it was often thought that the songs were encouraging people to revolt. The song "Va pensiero" from his opera "Nabucco" was about the Hebrew slaves who were captive in Babylon. People chanted it in the streets with the words suitably changed. Verdi became a great national hero. Italy eventually became one country in 1861.