 Having concentrated , the combined Allied force began marching north towards Medina @-@ Sidonia on 28 February , and la Peña now ordered Beguines 's irregulars to join them at Casas Viejas . Once there , however , Beguines 's scouts reported that Medina @-@ Sidonia was held more strongly than had been anticipated . Rather than engaging the French and forcing Victor to weaken his siege by committing more of his troops to the town 's defence , la Peña decided that the Allied army should march across country and join the road that ran from Tarifa , through Vejer and Chiclana , to Cádiz . 
