Complex sentence: Ruddy After Dubois established that the action had been sanctioned by the British, some of the prisoners were released after promising not to take up arms again; 21 prisoners were sent to the American camp outside Quebec.
Split into simpler sentences: Ruddy After Dubois established that the action had been sanctioned by the British, some of the prisoners were released after promising not to take up arms again. The remaining 21 prisoners were sent to the American camp outside Quebec.