Robert the Bruce was not yet King of the Scots when he stabbed John Comyn in front of the high altar in Greyfriars' Church in Dumfries. But he would be, pretty soon, in spite of being excommunicated for violence in the church. We explain the fight for the crown of Scotland and the interfering bossiness of Edward I of England, but we don't explain whether the Bruce murdered Comyn or it was self-defense, because we don't really know.  Because chroniclers.