Complex sentence: He passes down an official papal ruling that Father Gabriel's mission must be closed, and the plantation owners and colonists at the foot of the falls begin to plan their first raid on the Guarani's and the mission.
Split into simpler sentences: He passes down an official polciy decision that Father Gabriel's mission must be closed. The plantation owners and colonists at the foot of the falls begin to plan their first raid on the Guarani's and the mission.