After Túrin Turambar came to Nargothrond and became high in the councils of Lord Orodreth, he persuaded him to build a mighty bridge spanning the Narog. Now abandoning their secretive ways in favor of open warfare, the bridge was large enough to carry an equally large army. Its only flaw was it could not be lifted to prevent an enemy from coming across it, moreover it revealed the Elven realm to the servants of Morgoth thus dooming it.
At the bidding of Túrin, the Host of Nargothrond marched across the bridge to their doom on the field of Tumhalad. With the field of battle lost, the bridge in the end served as an easy road for its enemies and the dragon Glaurung leading to the Sack of Nargothrond.