Complex sentence: He identified four reasons which exacerbated the situation: lack of discipline, standard of food, lack of recreation, slow postal service and the cumulative result of these problems creating "indescribable filth in some of the ships".
Split into simpler sentences: He identified four reasons which exacerbated the situation: lack of discipline, standard of food, lack of recreation, and slow postal service. The cumulative result of these problems creating "indescribable filth in some of the ships".