Fortresses along Daugava

The Daugava River is among ten biggest streams in Europe. Importance of this international communication and trade route was generally undisturbed since the Viking age (6th – 9th century AD) until mid-19th century when the railway era begun. The first evidence of military actions in the Daugava valley was discovered by archaeologists; from 11th century onwards, there are also textual sources of information on the subject. High and somewhere rocky banks of the river made Daugava into a serious obstacle for troops and thus a terrain for one easier to defend, a kind of natural front line in war.