The River Soar () is a major tributary of the River Trent in the English East Midlands and is the principal river of Leicestershire. The source of the river is midway between Hinckley and Lutterworth. The river then flows north through Leicester, where it is joined by the Grand Union Canal. Continuing on through the Leicestershire Soar Valley, it passes Loughborough and Kegworth until it reaches the Trent at the county boundary. In the 18th century, the Soar was made navigable, initially between Loughborough and the Trent, and then through to Leicester. It was not until the early 19th century that it was linked by the Grand Union Canal to the wider network to the south and to London. Name The name of the Soar is included in a family of old river-names derived from a root *ser- "to flow", alongside (among others) Saravus (Soar, a tributary of the Moselle in Belgium), Sera (la Serre, la Cère and le Séran, three rivers in France), Serantia (Sierentz, Alsace), Serma (Schremm, Brandenburg), Sora (Cwm Sorgwm, Wales), Sorna (die Zorn, Alsace), Sara (Saire), Saar(e) (Brandenburg), Saros (Sar, Spain), Sarius (Serio, Lombardy), Sarià (Lithuania), Saravus (Saar, Germany), Sarnivos (Sernf, Glarus), etc. According to a suggestion due to William Somner (1701) the Soar river may formerly have been called the Leir, from Brittonic *Ligera or *Ligora, cognate with the French Loire. This theory is based on the name of Leicester (as well as Loughborough and the village of Leire) being derived from the name of the river. Course The Soar rises near Wibtoft in Warwickshire, and flows north to join the Soar Brook near Sharnford, it then continues in a north-easterly direction, passing through Croft and between Narborough and Littlethorpe, until on the outskirts of Leicester it is joined by the Sence near Enderby. Before flowing through the centre of the city it meets the Grand Union Canal at Aylestone, where it is also joined by the River Biam. After passing over Freemens Weir, the river splits and recombines with the canal, creating an area of Leicester called Bede Island. The navigable arm that runs to the east has been canalised with parallel banks and is known as ‘The Mile Straight’. Beyond Blackfriars, the river splits again to form Frog Island and Abbey Park; it recombines at Belgrave where it passes beside the National Space Centre. Once out of the city the Soar passes Birstall