Complex sentence: York was outnumbered by more than three to one, that evening York, his two sons, along with Warwick and Salisbury fled from the battle that could not be won, to Calais and Ireland.
Split into simpler sentences: York was outnumbered by more than three to one. That evening York, his two sons, along with Warwick and Salisbury fled from the battle that could not be won to Calais and Ireland.