Complex sentence: A peace treaty returned the Aragonese their previous possessions in 1388, but tensions continued and in 1391 the Arborean army led by Brancaleone Doria again swept the most of the island into Arborean rule.
Split into simpler sentences: A peace treaty returned the Aragonese their previous possessions in 1388, but tensions continued. In 1391 the Arborean army, led by Brancaleone Doria, again conquered most of the island subjecting it to Arborean rule.