Complex sentence: Another skirmish took place several days later, when the English engaged Frenchmen who had disembarked from ships retreating from Portsmouth, looking for fresh water, and a senior French commander, Chevalier D'Aux, was killed.
Split into simpler sentences: Another skirmish took place several days later, when the English engaged Frenchmen, disembarked from ships retreating from Portsmouth to look for fresh water. A senior French commander, Chevalier D'Aux, was killed.