Stephen reconnoitred Bristol in 1138 but decided that the town was impregnable. As his chronicler reported: "On one side of it, where it is considered more exposed to siege and more accessible, a castle rising on a vast mound, strengthened by wall and battlements, towers and divers engines, prevents an enemy's approach."Gesta Stephani ed. and trans. K.R. Potter (Oxford : Clarendon Press, 1976), pp. 37–8, 43–4. After Stephen was captured in 1141, he was imprisoned in Bristol Castle until Robert of Gloucester was also captured and an exchange of prisoners was made.William of Malmesbury, The Historia Novella, trans. K. R. Potter (London : T. Nelson, 1955), p.50.
