Complex sentence: The Coalition generals still hoped to bring Napoleon to battle against their combined forces, however after Arcis-sur-Aube Napoleon realising that he could no longer continue with his current strategy of defeating the Coalition armies in detail, decided to change his tactics.
Split into simpler sentences: The Coalition generals initial still hoped to bring Napoleon to battle against their combined forces. However after Arcis-sur-Aube Napoleon realising that he could no longer continue with his current strategy of defeating the Coalition armies in detail, decided to change his tactics.