Complex sentence: The escape of he Archbishop was perceived by Louis V as treason; he turned violently against Adalberon and threatened him to besiege Reims, with the matter being finally settled in a trial court at Compiègne.
Split into simpler sentences: The escape of the Archbishop was perceived by Louis V as treason; he turned violently against Adalberon and threatened him with a siege of Reims. The matter was finally settled in a trial court at Compiègne.