Complex sentence: O'Reilly analyzed what had gone wrong with the defenses of Havana during the successful British siege in 1762, and recommended sweeping reforms to improve the fortifications, training, practices, and troop organizations, which were quickly approved by the Spanish Crown.
Split into simpler sentences: O'Reilly analyzed what had gone wrong with the defenses of Havana during the successful British siege in 1762. He recommended sweeping reforms to improve the fortifications, training, practices, and troop organizations, which were quickly approved by the Spanish Crown.