 The coal export trade from the Wear was slow to develop, but by the seventeenth century there was a thriving trade in exporting coal from the Durham coalfield via the River Wear.The tonnage however was much smaller than on the Tyne; in 1609, 11,648 tons were exported from the Wear compared with 239,000 tons exported from the Tyne.This imbalance changed dramatically during the English Civil War because of the Parliamentarian blockade of the Tyne and their encouragement of the Wearside merchants to make up for the subsequent shortfall in coal for London.