Complex sentence: In more general terms, the battle was a considerable boost to the Lacaedemonian's morale and prestige, since after the disaster at Pylos they had been considered cowardly and incompetent in battle.
Split into simpler sentences: In more general terms, the battle was a considerable boost to the Lacaedemonians morale and prestige. For, after the disaster at Pylos, they had been considered cowardly and incompetent in battle.