Complex sentence: The French were victorious in the Second Battle of Puebla on 17 May 1863, and within a month the capital Mexico City fell, forcing Juárez's government into exile in the remote north.
Split into simpler sentences: The French were eventually victorious, winning the Second Battle of Puebla on 17 May 1863 and pushing on to Mexico City. When the capital fell, Juárez's government was forced into exile in the remote north.