Complex sentence: Atahualpa's generals won a decisive victory, shattering Huáscar's army once again and capturing himself, and shortly after conquering his capital Cusco for Atahualpa.
Split into simpler sentences: Atahualpa's generals won a decisive victory. They shattered Huáscar's army once again, captured Huáscar himself, and shortly thereafter conquered his capital Cusco for Atahualpa.