Como Gollum sabia que Sauron estava reunindo os Haradrim para fazer guerra?

Gollum sabe o que é conhecimento comum entre os servos de Sauron

No livro As Duas Torres, Sam faz a Gollum mais ou menos a mesma pergunta que você, de uma maneira normalmente suspeita:

‘No, no indeed,’ said Gollum. ‘Hobbits must see, must try to understand. He does not expect attack that way. His Eye is all round, but it attends more to some places than to others. He can’t see everything all at once, not yet. You see, He has conquered all the country west of the Shadowy Mountains down to the River, and He holds the bridges now. He thinks no one can come to the Moontower without fighting big battle at the bridges, or getting lots of boats which they cannot hide and He will know about.’

‘You seem to know a lot about what He’s doing and thinking,’ said Sam. ‘Have you been talking to Him lately? Or just hobnobbing with Orcs?’

‘Not nice hobbit, not sensible,’ said Gollum, giving Sam an angry glance and turning to Frodo. ‘Sméagol has talked to Orcs, yes of course, before he met master, and to many peoples: he has walked very far. And what he says now many peoples are saying. It’s here in the North that the big danger is for Him, and for us. He will come out of the Black Gate one day, one day soon. That is the only way big armies can come. But away down west He is not afraid, and there are the Silent Watchers.’

A resposta de Gollum faz sentido, já que ele havia passado algum tempo em Mordor anteriormente e deve ter ouvido muita conversa de vários orcs durante seu tempo lá.

... e o resto é fácil de deduzir ao ver os Haradrim.

Quando os Haradrim aparecem, bem perto de onde o trio está descansando, Gollum se aproxima para observá-los, e o resto é uma dedução simples:

‘More Men going to Mordor,’ he said in a low voice. ‘Dark faces. We have not seen Men like these before, no, Sméagol has not. They are fierce. They have black eyes, and long black hair, and gold rings in their ears; yes, lots of beautiful gold. And some have red paint on their cheeks, and red cloaks; and their flags are red, and the tips of their spears; and they have round shields, yellow and black with big spikes. Not nice; very cruel wicked Men they look. Almost as bad as Orcs, and much bigger. Sméagol thinks they have come out of the South beyond the Great River’s end: they came up that road. They have passed on to the Black Gate; but more may follow. Always more people coming to Mordor. One day all the peoples will be inside.’

Eles são claramente aliados de Sauron, pelo fato de marcharem tão aberta e casualmente na própria fronteira de Mordor. E eles parecem ser do sul, tanto pela aparência quanto pelo fato de estarem subindo a estrada sul para o Morannon.

He's been hiding under a mountain for years, and when he wasn't hiding under a mountain, he was stalking the Fellowship. The point is that his activities would not put him in contact with people who would know Sauron's plans.

Bilbo era apenas 50 quando partiu em sua missão. Ele vira o 51 enquanto monta no cano, então ele é o 51 quando chega a Esgaroth, em Long Lake.

Bilbo então mantém o anel até seu 111^th aniversário, quando ele (com muita relutância) deixa para Frodo. Frodo e Bilbo compartilharam o mesmo aniversário, então Frodo virou 33 quando recebeu o anel.

Então Frodo tem o anel por algum tempo. Ele é 50 quando Gandalf retorna e o coloca no fogo para confirmar sua verdadeira identidade.

Então, há aproximadamente 77 anos desde que Bilbo conseguiu o anel pela primeira vez, até Gandalf revelar a Frodo o que o anel realmente é.

Então, o que Gollum fez durante esse tempo? Ele permaneceu nas montanhas por um pouco disso, mas apenas um pouco. No início da Irmandade, Gandalf diz:

Oh yes, he came out. His longing for the Ring proved stronger than his fear of the orcs, or even of the light. After a year or two, he left the mountains.

Então, Gollum teve cerca de 10 anos para viajar pela Terra Média, reunir notícias e tentar encontrar Bilbo:

'[...] He found his way into Mirkwood, as one would expect.'
'Is that where you found him?' asked Frodo.
'I saw him there', answered Gandalf, 'but before that he had wandered far, following Bilbo's trail.'
'[...] from hints dropped among the snarls I even gathered this his padding feet had taken him at least to Esgaroth, and even to the streets of Dale, listening secretly and peering.'
'[...] But at last, when I had given up the chase and turned to other parts, Gollum was found. My friend [Aragorn] returned out of great perils bringing the miserable creature with him.'
"What he had been doing he would not say. He only wept and called us cruel, with many a gollum in his throat; and when we pressed him, he whined and cringed, and rubbed his long hands, as if he remembered some old torture. But I am afraid there is no possible doubt he had made his slow, sneaking way, step by step, mile by mile, south, down at last to the land of Mordor."

Resumo

Gollum / Smeagol teve cerca de 10 anos para reunir notícias do anel, Mordor e Sauron (e perseguir Bilbo) - e ele fez uso desse tempo, viajando por toda a Terra Média e coletando notícias. Além disso, sua longa associação com o anel desenha ele para as partes da Terra Média, como Mirkwood e Mordor, que estão intimamente associadas a Sauron, levando a uma quantidade considerável de informações sobre Sauron e suas intenções.

Dois pontos:

Primeiro, como poderia qualquer um no sul da Terra-média não tem conhecimento disso? Sauron vinha aumentando sua pressão sobre Gondor há anos, e os exércitos reunidos em Mordor só podiam significar uma coisa. E Gollum tinha um padrão estabelecido de espionagem e escuta.

Segundo, Gollum já fora cativo de Sauron e foi torturado. Sauron tinha um padrão estabelecido de se gabar de seus inimigos capturados, e mesmo que Sauron não monologasse em Gollum, os orcs que teriam sido seus principais carcereiros / torturadores teriam se gabado. E eles sabiam muito do que estava acontecendo e fofocavam. Por exemplo:

'Oho! So they haven't told you what to expect? They don't tell us all they know, do they? Not by half. But they can make mistakes, even the Top Ones can.'

'Sh, Gorbag!' Shagrat's voice was lowered, so that even with his strangely sharpened hearing Sam could only just catch what was said. 'They may, but they've got eyes and ears everywhere; some among my lot, as like as not. But there's no doubt about it, they're troubled about something. The Nazgûl down below are, by your account; and Lugbúrz is too. Something nearly slipped.'

'Nearly, you say! ' said Gorbag.

'All right,' said Shagrat, 'but we'll talk of that later: Wait till we get to the Under-way. There's a place there where we can talk a bit, while the lads go on.'