 York Castle fell into disrepair by the 15th and 16th centuries, becoming used increasingly as a jail for both local felons and political prisoners.By the time of Elizabeth I the castle was estimated to have lost all of its military value but was maintained as a centre of royal authority in York.The outbreak of the English Civil War in 1642 saw York Castle being repaired and refortified, playing a part in the Royalist defence of York in 1644 against Parliamentary forces.