Complex sentence: The Satsuma Rebellion, a revolt of disaffected samurai in Japan, breaks out against the new imperial government; it lasts until September, when it is crushed by a professionally led army of draftees.
Split into simpler sentences: The Satsuma Rebellion, a revolt of disaffected samurai in Japan against the new imperial government. The Rebellion lasts until September of that year when it is crushed by a professionally led army of draftees.