Complex sentence: In 668 the Battle of Fertas (near Belfast) was fought between the Ulaid (Dal Fiatach) and the Cruithne (or Dal nAraide) and Cathussach mac Luirgéne, their king, was defeated and slain.
Split into simpler sentences: In 668 the Battle of Fertas (near Belfast) was fought between the Ulaid and the Cruithne. Here, Cathussach mac Luirgéne, their king, was defeated and slain.