With Osgiliath safe for passage, Mablung sends you on to assist Angbor at the Cross-roads.
'A vanguard of Lord Aragorn's Host has passed through Osgiliath and gone on to the Cross-roads. Angbor, Lord of Lamedon, leads these men in securing that place and preparing the way. I deem it is an undertaking that will require many hands.'
You should travel to the Cross-roads, which lie east of after-battle Osgiliath.
You should talk to Angbor, who can be found at the after-battle Cross-roads.
View the statue at the after-battle Cross-roads.
You should talk to Angbor, who can be found at the after-battle Cross-roads.