The River Shannon (Irish: Sionainn altenatively Sionna), Ireland's longest river, divides the West of Ireland (mostly the province of Connacht) from the east and south (Leinster and most of Munster). The river has been an important waterway since antiquity. First mapped by Ptolemy, the river is 386 km (240 mi) long, and thus it exceeds the length of all other rivers in Ireland. The river flows generally south from the Shannon Pot in County Cavan before turning west and emptying into the Atlantic Ocean through the 113 km (70 mi) long Shannon Estuary. Limerick city stands watch at the point where the river water meets the sea water of the estuary. Only east of Limerick is the river no longer affected by the tides.

Geography

The source of the Shannon is in the Cuilcagh Mountains in south County Fermanagh in Northern Ireland, from where it flows through Shannon Cave, and rises at Shannon Pot in County Cavan. The river runs through/between 13 of Ireland's 32 Counties. Lakes on the Shannon include Lough Allen, Lough Ree and Lough Derg. Tributaries include the River Inny, River Suck and the River Brosna.

It is linked to the River Erne by the Shannon-Erne Waterway.

History

The river began flowing along its present course after the end of the Ice Age. Vikings settled in the region in 10th century and used the river to raid the rich monasteries deep inland. In 937 the Limerick Vikings clashed with those of Dublin on Lough Ree and were defeated.

In the seventeenth century, the Shannon was of major strategic importance in military campaign in Ireland, as it formed a physical boundary between the east and west of the country. In the Irish Confederate Wars of 1641-53, the Irish retreated behind the Shannon in 1650 and held out for two further years against English Parliamentarian forces. In preparing a land settlement, or plantation after his conquest of Ireland Oliver Cromwell reputedly said the remaining Irish landowners would go to "Hell or Connaught", referring to their choice of forced migration across the river, or death.

In the Williamite war in Ireland (1689-91), the Jacobites also retreated behind the Shannon after their defeat at the Battle of the BoyneSieges of Limerick and Siege of Athlone). in 1690. Athlone and Limerick, cities commanding bridges over the river, saw bloody sieges. (See

As late as 1916, the leaders of the Easter Rising planned to have their forces in the west "hold the line of the Shannon". However, in the event, the rebels were neither well enough armed nor equipped to attempt such an ambitious policy.

The Shannon holds much of Irelands past and is a beautiful site to see.

Economics

Despite being more than 300 km (200 miles) long, it rises only 76 m (250 feet) above sea level, so the river is easily navigable, with only a few locks along its length. There is a hydroelectric generation plant at Ardnacrusha belonging to the ESB.

Shipping in Shannon estuary was developed extensively during the 1980s, with over £2 billion (€2.5Billion) investment. A tanker terminal at Foynes and an oil jetty at Shannon Airport were built. In 1982 a large scale Alumina Extraction Plant was built at Aughinish. 60,000 tonne cargo vessels now carry raw bauxite from West African mines to the plant, where it is refined to Alumina. This is then exported to Canada where it is further refined to Aluminium. 1985 saw the opening of a huge coal-fired electricity plant at Moneypoint, fed by regular visits by 150,000 tonne bulk carriers.