The River Blackwater is a river in Essex, England. It rises as the River Pant in the northwest of the county, just east of Saffron Walden, and flows in a generally southeast direction to Bocking, near Braintree, via Great Sampford and Great Bardfield. At Bocking, it becomes the River Blackwater, and veers east to flow past Bradwell Juxta Coggeshall and Coggeshall. It then veers south, flowing past Kelvedon and Witham, before reaching Maldon. There, it veers east again and empties into the Blackwater Estuary, which in turn meets the North Sea at Mersea Island. The River Blackwater has two major tributaries: the River Brain, which meets it just south of Witham, and the River Chelmer, which meets it just east of Maldon. The lower reaches of the Chelmer, from Chelmsford, were canalised in the 1790s, and the navigation diverts water north of the Blackwater through Maldon before emptying into the Blackwater Estuary at Heybridge Basin. History One of the most famous Viking battles in Britain, the Battle of Maldon, possibly took place at the mouth of the river in 991. The Battle of Maldon, an early-11th-century fragmentary poem which describes the battle, mentions the Panta and describes a tidal causeway which could be the causeway leading to Northey Island. The Saxons were defeated and their leader, Byrhtnoth, was killed. The Blackwater was a source of fish and oysters for the town of Maldon during the Roman occupation. The remains of Saxon fish traps were discovered in the river in the 1990s. During the winter of 1776 the Blackwater froze from Maldon to Osea island, a distance of some four miles. The ice trapped fishing and cargo carrying vessels and blocked any imports of coal, oil, wool to Maldon. In 1793 the Chelmer and Blackwater Navigation Company was formed by act of Parliament. Over the next four years, the company built a navigation from Chelmsford to meet the tidal estuary of the River Blackwater in Colliers Reach at the place that is today called Heybridge Basin (after the canal basin there). The burgers of the borough of Maldon refused to allow the canal to pass through their borough, so the company routed it just outside the borough boundary, which is why it ended up at Colliers Reach, rather than at Maldon. From Chelmsford, the navigation mainly followed the course of the River Chelmer until it reached Beeleigh, near Maldon. Then it