Complex sentence: Annoyed at the evacuation of Asturias, he directed that it should be reoccupied by the Army of the North, and, whilst Oviedo and Gijón were taken with ease, the result was that the unfortunate Dorsenne had to hold down more territory.
Split into simpler sentences: Annoyed at the evacuation of Asturias, he directed that it should be reoccupied by the Army of the North. While Oviedo and Gijón had been taken with ease, but Dorsenne had to hold down more territory.