Complex sentence: In early November, Governor Clayton cancelled all elections and declared martial law, splitting the state into four military districts, putting Upham in charge of the Northeastern district, which had the most Klan activity.
Split into simpler sentences: In early November, Governor Clayton cancelled all elections and declared martial law, splitting the state into four military districts. Upham was put in charge of the Northeastern district, which had the heaviest amount of Klan activity.