"Castelh Gwent" on the Cambriae Typus map of 1573. The castle and town changed hands several times during the English Civil War, and the regicide Henry Marten was later imprisoned and died in the castle. The port continued to flourish; during the period 1790 to 1795, records show a greater tonnage of goods handled than Swansea, Cardiff and Newport combined. Chepstow reached the peak of its importance during the Napoleonic Wars, when its exports of timber, for ships, and bark, for leather tanning, were especially vital. There were also exports of wire and paper, made in the many mills on the tributaries of the Wye. An important aspect of Chepstow's trade was entrepôt trade: bringing larger cargoes into the manageable deep water of the Wye on high tide and breaking down the load for on-shipment in the many trows up the Wye to Hereford past the coin stamping mill at Redbrook, or up the Severn to Gloucester and beyond. Chepstow also traded across the estuary to Bristol on suitable tides to work vessels up and down the Avon to that city's centre. Many buildings in the town remain from the late 18th and early 19th centuries; the elegant cast iron bridge across the Wye was opened in 1816 to replace an earlier wooden structure. The town became an important centre for tourism from the late eighteenth century, when the "Wye Tour" became popular. Visitors regularly took boats from Ross-on-Wye and Monmouth down the river, visiting, drawing and painting the "picturesque" views of the area, which included those of Tintern Abbey, Piercefield House, and the ruined Chepstow Castle. In the 19th century a shipbuilding industry developed, and the town was also known for the production of clocks, bells, and grindstones. In 1840 leaders of the Chartist insurrection in Newport were transported from Chepstow to Van Diemen's Land. The port's trade declined after the early 19th century, as Cardiff, Newport and Swansea became more suitable for handling the bulk export of coal and steel from the Glamorganshire and Monmouthshire valleys. However, shipbuilding was briefly revived when the National Shipyard No.1 was established during the First World War and for a short period afterwards, when the first prefabricated ships, including the War Glory, were constructed there. The influx of labour for the shipyards, from 1917, led to the start of "garden suburb" housing development at Hardwick (now known locally as "Garden City") and