The Host of the West marches from Minas Tirith.
Frodo comes in sight of the Isenmouthe; he is overtaken by Orcs on the road from Durthang to Udûn.
Aragorn is on his way to the Black Gates of Mordor and Sauron knows this, he’s ordered his armies to march to the Black Gate. One of these groups runs into Frodo and Sam disguised as Orcs.
There’s a cool moment in the Extended Edition of The Return of the King where we actually get to see Frodo and Sam accidentally run into a pack of Orcs.
After Cirith Ungol, Frodo and Sam disguise themselves as Orcs and continue their journey into Mordor. Modor, however, seems deserted. For a while they’re able to walk into Mordor and make their way, they’re relieved their presence hasn’t already been detected. So, they press on, as they’re traveling panic hits as they begin to hear Orcs heading their way. There’s no where to hide and they have to slouch on the road pretending to rest. Orcs pass them by but when the Orc driver/leader/quartermaster finds them and forces them to join formation.
Frodo and Sam are now on their way to the Black Gate and Sam’s mind is all over the place trying to figure out how to get them free.
Thank you for your time and remember, the crownless again shall be king.
– The Wandering One