The Army of the West marched along the Causeway to Osgiliath and on for 5 miles to their first camp. The next day Gandalf and Aragorn rode as far as the bridge leading to Minas Morgul, which they destroyed. That night they camped close to the Crossroads. (The Black Gate Opens; Bk 3).
They marched north and towards the end of the second day’s march from the Crossroads they reached the cutting where Frodo and Sam had turned off the road and where the Battle with the Oliphaunt took place, and there fought off an ambush. On the fifth day after the Crossroads they made their last camp, after turning away from the road to approach Morannon from the north-west.
They drew up the army – now only 6,000 strong – on two hills before the Black Gate. On one hill was Gandalf and the men of Minas Tirith, on the other the men of Rohan and those from the south. In the van were Aragorn and the Dunedain, Prince Imrahil and the pick of the Tower Guard. (The Black Gate Opens; Bk 3).
This map also shows the Field of Cormallen which was within earshot of the Falls of Henneth Annun, and the route down to Cair Andros where the victors took ship and sailed down river to Osgiliath and so back to Minas Tirith. (The Field of Cormallen; Bk 3).