In the battle at the black gate, 60000 soldiers from many regions of mordor. OF MORDOR. Not the surrounding area, in fact, from the chapter in wich <PERSON> and <PERSON> and <PERSON> wander through mordor, its implied sauron just hastily put together a force to crush all opposition in the battle of the morannon. So the ENTIRE ARMY of mordor and ALL ITS ALLIES must have been at least a hundred thousand. And the army of isengard at its full capacity likely could not have reached 20000, i think not more than 17000 unless he continued breeding orcs and arming them, then he would have 20000, probaly including the dunlendings. EDIT: TLOTR ROTK chapter 3 "In that dale behind the morannon were the tunnels and deep armouries that the servants of Mordor had made forthe defence of the Black Gate of their land; and there now their Lord was gathering *in haste great forces to meat the onslaugth of the Captains of the West."
I think this had something to do with <PERSON>'s defeat at Minas Tirith, i mean this as in; his forces are scattered, the captains of the west are coming for his doorstep (he was monitoring them with his other black riders), and the Witch King was dead. So he quickly calls another finger of his ultimate force (more on that later) destined to crush the captains of the west for good, so he did. So, about that finger. To quote <PERSON> in LOTR ROTK The pyre of denethor; "For a little space you may triumph on the field, for a day. But against the power that now arises there is no victory. To this City only the first finger of its hand has yet been stretched. All the east is moving."
Since <PERSON> has seen <PERSON>'s forces through the <PERSON> himself (remember, even <PERSON> can't make <PERSON> see things that are not there, so <PERSON> MUST know the true size of <PERSON>'s grand army), im assuming that means im in for some math. So its said the forces of the Southern warriors number three times the size of the original force of <PERSON>; LOTR ROTK The battle of the pelennor fields "And if the Rohirrim at their onset were thrice outnumbered by the Haradrim alone, soon their case became worse;"
Well... 381
Im not putting another quote, but the Rohirrim at their onset numbered 6000, so the force of Mordor at the City numbered at the very least 20000, i'd say around 40000. So if that force is but a finger of <PERSON>'s hand, and <PERSON> has 9 fingers (nine fingers, so that influences his entire army size. thats... WHATEVER)... well, <PERSON> has at least 500000 troops. Thats more than the entire roman army. And they didn't even need all of it to take over all of Greece, Egypt, Italy, and more which honestly couldn't really provide any true resistance.
Now, to finish, i think <PERSON> COULD have gathered 20000 troops. Why? Welp, you saw it coming; a quote from <PERSON> king; <PERSON> The road to <PERSON> "But there are not men enough in the mark, not if they are all gathered together and healed of wounds and weariness, to assault the stronghold of sauroman."
<PERSON> is saying here that even when he knows at least 10000 of Saurumans orcs and men were defeated a while ago, Sauruman still has the strength to halt any attack. He's saying that even if all men in the mark rallied together, it still wouldn't be enough to launch an attack. And that number can be up to 14000. Also Theoden likely also means manpower, its obvious you can't take the tower of Orthanc, because its unbreakable, but later he is also suprised at how <PERSON>'s entire force is scattered when he arrives at Orthanc (well, actually everyone in the company was, including <PERSON>), so all in all its implied <PERSON> must still have some force at isengard after sending most of his troops away. So thats my conclusion. And also my concussion, i am very flustered.
Extra edit: what? the 60K? well, yeah, 60K at least, but i highly doubt its that much more. perhaps 62000, but no more. 88