Complex sentence: In 1495 Pontremoli was sacked by the troops of Charles VIII of France, during this time Pontremoli was a territory owned by the House of Sforza, who were the new Dukes of Milan.
Split into simpler sentences: In 1495 Pontremoli was sacked by the troops of Charles VIII of France. During this time Pontremoli was a territory owned by the House of Sforza, who were the new Dukes of Milan.