Complex sentence: From the mid- 19th century on, the city attracted many Irish and German Catholic immigrants during their large mid- 19th-century emigrations from Europe: the Irish fleeing the Great Famine and Germans coming after the Revolutions in the German states of 1848.
Split into simpler sentences: From the mid- 19th century on, the city attracted many Irish and German Catholic immigrants. The Irish were fleeing the Great Famine and Germans came after the Revolutions in the German states of 1848.