Complex sentence: The Britons pleaded for aide from Rome once more, but Rome had abandoned Britain to the ravages of the invaders, so they asked Guithelinus, the Archbishop of London, to seek help from their Briton cousins in Brittany.
Split into simpler sentences: The Britons pleaded for aide from Rome once more, but Rome had abandoned Britain to the ravages of the invaders. They asked Guithelinus, the Archbishop of London, to seek help from the Britons in Brittany.