Complex sentence: Italian nationalism first arose as a potent political force in the 1830s in the Italian peninsula under the leadership of Giuseppe Mazzini and served as a cause for "Risorgimento" in the 1860s to 1870s.
Split into simpler sentences: Italian nationalism first arose as a potent political force in the 1830s in the Italian peninsula under the leadership of Giuseppe Mazzini. It served as a cause for "Risorgimento" in the 1860s to 1870s.