Complex sentence: Fergal was killed, along with many others, at the battle of Almain, in 722, fought against Murchad mac Brain of the Uí Dúnlainge, the king of Leinster.
Split into simpler sentences: Fergal was killed, along with many others, at the battle of Almain, in 722. This battle had been fought against Murchad mac Brain of the Uí Dúnlainge, the king of Leinster.