This study argues that when the Royalists captured Bristol in July 1643 they gained not only the city but also the materials and facilities that quite literally allowed them to remain in the war. Under Royalist rule Bristol became a vital centre for military and government activities. Its position as a focus of communications between the west of England, south Wales and Ireland, combined with plentiful accommodation and comparative security, made the city an ideal location for equipping new units. The loss of Bristol in 1645 was therefore a huge blow to the Royalist cause: it now became a parliamentary garrison and a vital supply base for Cromwell's war in Ireland.