Stuck in Survive (Campaign)

When I played this Campaign it was pretty easy early on then once I had reached Madrid I got stuck Murat was always able to dish out more damage to my tier 4 Grenadiers and generals even with morale Murat was able to last longer than the the time I ran out of food I tried getting more farms but most of the farms were burnt and I sent Palafox alone to take barcelona But once he reached ther he was insanley low and then my Food ran out.