In 997 according to the
Anglo-Saxon Chronicle, raiding Vikings travelled up the Tamar and then the Tavy river as far as
Lydford, and burned
Ordwulf's monastery at
Tavistock. During the
English Civil War,
Cornwall was entirely loyal to
King Charles I and the
Royalist cause. However,
Devon was primarily
Parliamentarian; thus the River Tamar became the site of many battles, such as the
Battle of Gunnislake New Bridge on 20 July 1664. Each side of the Tamar understood that if they were either to invade or to defend themselves, they had to have control of the Tamar crossings. In medieval times the transport of goods to supply the Benedictine abbey at
Tavistock, four miles by
track from the river port of Morwellham, was significant. Sea sand from the coast was imported to spread on farmland, until in the 18th century a dressing of
lime was found to be more beneficial. Large quantities of limestone and coal were then imported to burn in the numerous
limekilns on the river quays; the lime had to be made locally as it was not
slaked before application, and was too chemically reactive for transport by water after burning. Later, street sweepings and other refuse from
Plymouth and
Devonport, together with bones for the newly discovered
bone fertiliser, were carried inland to manure the fields. Other regular imports were timber from
British Columbia and the
Baltic, in large
baulks for use as
pit props in the mines, and coal from Wales to supply the mine pumping engines.
Tavistock was one of the three
stannary towns of Devon, and large quantities of
refined tin ore were exported through Morwellham from the 12th century until 1838, when the requirement to pay duty on the metal at one of the specified towns was relaxed. Other significant cargoes exported were quarried granite, and later, copper, lead and manganese ores, with their important by-product of
arsenic. Arsenic was extracted from
mispickel, once regarded as a waste product but later offering an important source of revenue as copper and tin extraction declined in profitability. The refined product was exported worldwide, in particular to the southern United States, where it was used as an insecticide in the cotton fields. In the 13th century lead and silver output from the royal mines on the
Bere peninsula (between the Tamar and the
Tavy) was significant, and production continued intermittently until the 19th century. The
Johnson Matthey smelting works at Weir Quay extracted silver and lead not only from local ore, but also from ore imported by sea from Europe and from as far away as
Newfoundland. railway crosses the Tamar on a viaduct, built in 1907, at
Calstock. The old ferry crossings developed into the busy river quays of the 18th and 19th centuries. The development of the "
Three Towns" (Plymouth, Devonport and
Stonehouse) at the mouth of the river offered an important market for the valley's agricultural produce, needed in particular to serve the victualling requirements of the
royal dockyard, and this was always carried by boat. In 1820 or 1821 the first paddle steamer on the Tamar inaugurated a service between Calstock and Devonport to deliver foodstuffs. The growing city population created a large demand for sightseeing cruises on the river; this was a significant source of traffic from 1823, with the launch of the
Cornish steam packet Sir Francis Drake, until the outbreak of
World War II. Mineral traffic on the river diminished towards the end of the 19th century, after the
Plymouth, Devonport and South Western Junction Railway reached Tavistock in 1859 (so making the Tavistock Canal to Morwellham redundant for transport, although it remains in use as a source of
hydropower) and as the copper and tin mines became exhausted. The decline accelerated from 1894, when the
East Cornwall Mineral Railway, until then linked to the outside world only through the port of Calstock, was extended to the
Plymouth, Devonport and South Western Junction Railway at
Bere Alston. Tourist and market traffic on the river, using purpose-built or converted steamers, remained substantial until the Devonport piers were closed and the ships requisitioned on the outbreak of war in 1939. == Economy ==