Complex sentence: Antipope Alexander V excommunicated him, calling Louis II of Anjou to Italy to conquer Naples; the count of Provence arrived in Italy in late July 1409 with 1,500 cavalry and was invested with the Neapolitan crown.
Split into simpler sentences: Antipope Alexander V excommunicated him, and called Louis II of Anjou back to Italy to conquer Naples. Louis arrived in late July 1409 with 1,500 cavalry and was invested with the Neapolitan crown.