A great battle in Caemlyn at the beginning of "A Memory of Light".

ToM Epilogue shows the beginning of the Shadow's invasion of Caemlyn through Waygate, as from the unread warning by Verin. This I think will be not a sideshow but one of the focus points of Tarmon Gaidon. I collected a large number of hints through the books that give us a glimpse of what's going to happen.

1) The Borderlands invasions and the stategic importance of Caemlyn in the Last Battle (ToM spoilers!!!)

Anyone with knowledge of events in ToM - especially those that are happening somehow in the background - cannot see that taking Caemlyn is a crucial strategic target for the Shadow. This would not be so were the Borderlands secure, but they are not anymore. The four Borderland rulers went in their quest for Rand taking most of their armies with them, leaving very weak garrisons in their lands. Why they felt compelled to bring so much military power on that quest at the cost of leaving their lands open to invasion is an open question - possibly one third or even one tenth of that huge force could have been enough.
Sure, there is no rule to evaluate what force you need to vanquish a false Dragon, had Rand proven to be so by not answering correctly the prophesized question. Sure enough, had Rand not passed the test, the world was doomed anyway. However, Rand being true, we still have the Borderlands invaded and their armies not yet into the fight at the end of ToM.

What is the situation in the Borderlands at the end of ToM, we know only from sparse hints, both in the Prologue and Epilogue of ToM, in Lan's march, and from the Battle for Maradon. Three focus points we are given. These are Maradon, Kandor and Tarwin's Gap. We know that Maradon has been attacked by a huge Shadow force, quantifiable in several hundred thousands (perhaps millions) Trollocs, with associated Fades and Draghkar, with the qualifying presence of male Dreadlords. And, had Rand not stepped in, they would have won, notwithstanding the defense - quite strong - by Rodel Ituralde and his 50000-strong battle-hardened Domani army with one hundred Asha'man, belatedly renforced by the Saldaeans in Maradon. Such considerable effort by the Shadow must not be overlooked, especially because of the male Dreadlords, that could have raised suspicions about the Black Tower's ploy. In fact, the Dreadlords show up briefly only when Yoeli chooses to commit what he sees as treason to let the reeling Ituralde's force within the walls. This stops the successful Darkfriend plot
(led by Torkumen) to refuse fight with the Shadow, and then Dreadlords are called in briefly and only to smash Maradon's walls from a distance.

Another focus point is Kandor. We have a glimpse on the overwhelming assault to the Kandori guard towers in ToM's Prologue, and we know that it succeeded - as an aside - by Barriga's POV in ToM's Epilogue. We know assume that this attack was very strong, maybe comparable to the attack to Maradon in strength. In fact, the guard towers not only fall but they fall so fast that many cannot even send warning flashes to the others. In ToM's Prologue we see Heeth Tower receiving just a single flash from Rena Tower before Rena quitting communications, while Farmay Tower goes mute without even that. As we have a good impression on how well these towers are built for defense and on the spirit of the defenders manning them form ToM's Prologue, the only way to crack them so fast is with a really large Shadowspawn force beefed up with Dreadlords. As perhaps in Maradon.

Tarwin's Gap - the classical attack avenue of the Shadow - is attacked only several weeks later and with a much smaller force. Lan (ToM's Epilogue) evaluates the force in front of him at 150000 Trollocs, which is much less than what was used in Maradon and probably also in Kandor. This strongly suggest that the push on Tarwin's Gap is a decoy, while the real push of the Shadow takes place in Saldaea and Kandor. No information is given about Arafel and Shienar, but Lan travels through them and unwillingly collects armed followers (ToM: Chapter 7, ToM: Chapter 23), especially at the Silverwall Keeps (ToM: Chapter 42) at the border between Kandor and Arafel. Notably Kendral, grandson of King Paitar of Arafel, and Kaisel, grandson of Queen Ethenielle of Kandor, are there to join up with him too. All these men joining up with Lan for a desperate attack on Malkier when their own lands are under such pressure might look a bit foolish, except that Nynaeve roused them up before the Shadow's attacks took place. Those attacks were so sudden and fast that possibly no news of them reached the men travelling in small groups to join up with Lan.

One question is why Lan did not get any hint of the invasion of the Borderlands while he traveled through all of them. This is surely useful to the plot - he has to reach Tarwin's Gap for some reason. On one side, Lan chooses the less easy but also less trafficked roads - he's of a mind to go to his suicide attack alone until close to the end. Then, in Saldaea the Shadow forces battle in Maradon and he likely passes far off that place. While crossing Kandor, however, he goes through the Plain of Lances - to the north. Well, he stays far from towers, towns and strongholds for the same reason; he may be passing through land already crossed by the Shadow, without knowing it, or the Shadow forces are still pinned on the strongholds he avoids. Notably, one'd expect Trollocs rampaging through he country but this seems not the case. Shadow forces may be acting disciplined and staying massed for further attack (or busy finishing to crack Kandor's defences).

The other aside from this situation is that - as already mentioned - on Tom's Epilogue Lan is able to launch a surprise attack on a force that is over twelve
times stronger that his. Long, long odds... however, if he gets some help (Rand finally detaching some forces to Tarwin's Gap? The Ogier maybe? Nynaeve and/or some Aes Sedai / Asha'man / Wise Ones?) then Lan's thread starts to have more sense plotwise than a suicide banzai charge. It has been built up too long to end up so. Also, if he were to face a force like at Maradon's the odds would be well within the impossibility region. As it is, the Shadow is concentrating elsewhere and he faces a much weaker - though still considerable - decoy force.

So the picture, if we collect all hints through ToM, is clear: the Borderland invasion has its weight concentrated to the West. And whilst the Saldaean push has been checked, the Kandori one is - as far as we know - successful and dangerously so. But what is the strategic significance of this for the Last Battle is unclear - unless we piece it together with the invasion of Caemlyn.

In fact, between the western Borderlands and Andor there is only a big no-man's land - the Black Hills, Caralain Grass and Braem Woods. Passage is better through Saldaea and Kandor, while from the Eastern Borderlands one must cross the Black Hills. It is an avenue suitable for large armies - as the Borderlander rulers already showed. Then the attack on Caemlyn takes on an entirely different light: a Shadow's stronghold in Andor, directly supported from the Blight through Kandor and the Black Hills region, will threaten all of the Light-held lands. This makes high strategic sense: the Shadow can choose where to attack and concentrate its forces there, while the Light armies must disperse to defend all lands separately. In turn, this will enhance division in the Light's camp or at least impede a necessary but difficult entente between Rand's forces and the Seanchan. A very dangerous turn for the Light - if in fact Caemlyn falls.

2) Prizes in Caemlyn

Apart from the strategic position of Caemlyn, there is a lot in Caemlyn for the Shadow to want to grab. Elayne is a primary target against Rand, of course; she's not in town at the moment of the invasion, but the Shadow would count on her being there - the invasion plan much predates Rand's challenge to Egwene. Of course then the Dragons - if the Shadow has a grasp of their power. But even more, a large stash of One Power objects, mostly ter'angreal, has been brought by Elayne from Ebou Dar to the Royal Palace. These include [KoD: Chapter 15] a (probable) Talisman of Growth, for extending the Ways; it could be of strategic interest for the Shadow, assuming they could and knew how to use it, for bringing Shadowspawn anywhere. Some more ter'angreal we know the use of, and there are several communication devices (more about them later) like a flat white bowl for looking at things far away and several items for talking to people a long way off, plus many more, that the Shadow would either want to use or to deny to the Light.

3) The dire situation of Caemlyn at the beginning of "A Memory of Light"

We knew of the planned invasion in ToM: Chapter 23 from Chesmal tricked by Elayne. No details are given, though, so no actions or only wrong actions (like reinforcing the borders) are taken by Elayne and Birgitte. Next time we hear of it is reading Verin's letter in ToM: Epilogue. It happens through the Waygate - Talmanes and Olver witness the fires from a distance. The Waygate is located in the New City (TEotW: Chapter 44) so the invaders are within the New City walls but probably not yet within the Inner City walls or at least the Royal Palace. The part of the Band of the Red Hand that remains near Caemlyn with Talmanes, about half of it by a crude estimate if only the Cairhienin went with Elayne, is camped close to the town (10 minutes ride) and can swiftly reach the Inner City and the Dragons, assuming they can avoid the Shadowspawn in the New City. Then, very likely they will have to show how proficient theyare with the new weapons because no quick help may be forthcoming (see below).

The timeline in Brandon's writing is not sharply defined, however, in the last chapters of ToM, we can assume a certain degree of simultaneity - things happen within one day of each other in different plotlines. The last gateways from Caemlyn that we know of are (ToM: Chapter 53) that made by Jur Grady to send Mat, Thom and Noal to the Tower of Ghenjei, then soon after Grady, Neald, Aes Sedai and Edarra make a larger one to send Perrin's army to the Field of Merrilor. Grady probably goes there too; he promised Mat to open gateways to bring him back to Caemlyn each day at noon, but he can do so from the Field of Merrilor as well. In the same chapter, in the Black Tower plotline, Pevara realizes that gateways do not work anymore. Next, in (ToM: Chapter 56), also Androl's group of Asha'man do realize the same (then Androl goes to meet Pevara). All that happens within a couple of days - but we have no explicit time sequence. Let's go to the point. My impression is that the Dreamspike that was switched on in the Black Tower is not only used to trap convertible Asha'man and Aes Sedai, but also to envelop Caemlyn during the invasion. The purpose of that is to trap the Light's forces within and to deny quick reinforcements that could endanger its success. In fact, Shadowspawn cannot use Gateways (only Forsaken and Dreadlords can) so the mobility bonus that Gateways offer is denied to the bulk of the Shadow's armies anyway; a Dreamspike then more than levels the field, as the Shadow forces can use Waygates anyway, uncaring for some losses due to Machin Shin. In this sense, a Dreamspike is a true strategic weapon.

But first, can a Dreamspike located in the Black Tower envelope Caemlyn? Does the device have sufficient range? The answer is, definitely yes. Although in the WoT books precise measures of distance are rare and far between, we have two precisely stated values:
1) the range of a Dreamspike. In ToM: Chapter 34, Neald and Gaul have been scouting and determined that Traveling works four leagues away from Perrin's camp. So, four leagues is the range of the Dreamspike, or the radius of the violet dome.
2) the distance from the Black Tower to Caemlyn. In KoD: Chapter 17, we learn that the Black Tower is two leagues south of Caemlyn. So definitely a Dreamspike in the Black Tower will include Caemlyn under the dome.

The main consequences for Caemlyn's battle are two:
A) just the forces remaining in Caemlyin - including Talmanes' part of the Band - will be able to join battle with the Shadow's army, at least for some time.
B) the alarm will not reach immediately the bulk of the Light's forces gathered in the Field of Merrilor.

4) Players

So, at the beginning we'll have a hard fight. The forces located in/around Caemlyn and who will join battle from the start on the Light's side are
- part of the Band, with Talmanes and Olver, hopefully gaining immediately access to the Dragons and to either the Inner City or the Royal Palace as a citadel;
- part of the Guard left in Caemlyn. Charlz Guybon, Birgitte and Morgase are with Elayne at the Field of Merrilor (ToM: Chapters 52, 56). As leadership, then, the most likely to take the situation in hand is Dyelin.

Note that the venture of Elayne to Cairhien and then to Merrilor is unknown to the Shadow at the moment the invasion was planned, more than one month earlier, when Verin was able to give the warning letter to Mat. So the Shadow plan should include a force large enough to smash whatever force Elayne could have in town. Let's then look what other forces are present and/or likely to join battle for the two sides.

Three groups of female channelers, currently present in Caemlyn, will possibly join battle on the Light's side. The Kin of course - they'd probably not refrain
from fighting Trollocs. It is doubtful they would know how to fight, but they could learn from the others. Then we have several former Damane in reeducation - those know all too well how to fight. Finally, some Windfinders should still be in Caemlyn to watch over their Bargain, and they'll join fight if just for self-defense. Aes Sedai, Wise Ones or (reliable) Asha'man - we don't know explicitly, but it's unlikely any of those (Light's side) are present. Channelers for the Shadow include a very dangerous Black sister (Duhara) already somewhere in town, plus of course Marillin Gemalphin and Falion Bhoda coming in with Lady Shiaine and Doilin Mellar. Some of the Forsaken are behind and probably with the invasion; in fact, I suspect Moridin to be the mastermind, likely with Moghedien as field commander and Demandred leading an auxiliary force (see below). Moghedien will not likely join battle herself, however, at least at the beginning, striking only when a worthy target (e.g. Nynaeve) would show up. It is possible some Black Asha'man will also join.

Then we have small armies gravitating around Caemlyn that possibly will join battle.
We have mercenary bands camped around Caemlyn, one league from the walls and about ten thousands strong. They may join battle in part, and they might do it on either side. Shadow emissaries might have hired part of them. Others might come on the Light's side when they see Shadowspawn.
We have Jarid Sarand's army. He's a likely player in Caemlyn, will also appear in AMoL's prologue with the first POV [The Great Hunt 2011]. Which side is unknown, very possibly for the Shadow. In fact, he may not know of the amnesty given to his wife. Representatives of Sarand have been seen in Lady Shiaine's house [CoT: Chapter 15]. Ellorien writes Elayne asking for the liberation of Elenia Sarand [ToM: Chapter 11, when Jarid is also last mentioned (as being still on the loose). Ellorien has also been called on by Duhara, the Black sister [ToM: Chapter 11] before writing that letter. It odors of ploy to convince Jarid (as Elayne will obviously reject the request) that for rescuing his wife he needs 'help' from another side ...? The reason the Shadow would need Jarid's help is simple. Someone must help opening the Waygate, otherwise a small guard is sufficient to guard such a narrow choke point. However many Trollocs you have on the other side they cannot come out more than a few at a time, the rest queueing and waiting for Machin Shin. So Jarid's men - or some of the mercenaries - would go in, surprise he Waygare guards, then open tha Waygate for Trollocs ... and probably end their usefulness as field rations for the invading army.

We have also a minor state's army lurking nearby - King Roedran's. He also gets a lot of mention in passing in the last few books, lastly for his no-show at Merrilor's [ToM: Chapter 56]. This is a much more complex player, as Roedran is suspected to be nothing less than the alias of Demandred. We have no confirmation of this, of course. It is a small but well-prepared army, as from Talmanes' description and impressions [KoD: Chapter 26], with Roedran that managed to unify Murandy's forces, no small feat, shrewdly using the Band as a threat. It remains mysterious as for aim and purpose. If it will side with the Light, we can't make any prediction. But if the opposite is true - and if Roedran is, in fact, Demandred - then he would be part of Moridin's plan. That can be surmised from Demandred's readiness report to Moridin [TGS: Prologue]. He would of course have a role that fits his highest aim - to kill Rand. This could be achieved by leading a counterstrike when a large Light force finally arrives to try to retake Caemlyn. The plan looks simple and effective: first, Caemlyn is invaded, and the Light is kept in the dark long enough for the invasion to succeed. Then, when finally the news reaches Rand, he'd be the one to lead a robust counterattack. To do so, he must Travel to outside the dome and then walk his army to the walls. At that point, Roedran-Demandred hits from the back and hammers Rand with Caemlyn's walls as anvil. Caemlyn's walls would be held, at that point, by the Shadow, includng Black Asha'man. Demandred would have the key to the Dreamspike [such thing exists, ToM: Chapter 5], enabling him to Travel straight in the dome, where Rand and his forces would be blocked.

5) How will it really go?

If the Shadow's plan would succeed, then the Shadow wins and the story is finished, so we can hope it will fail - at least in part. For one, as detailed above, the Shadow should find a much stiffer resistance in Caemlyn, lead by Talmanes and Dyelin, using Dragons and Damane. Olver could get a chance to use the knife he took [ToM: Epilogue] - it seems to me a fitting way for Doilin Mellar to end. The Black Asha'man could end the battle quickly, but I'd think they'll have some resistance to overcome first. We have a seed of internal organized resistance in the Black Tower with Androl (and friends) and Pevara [ToM: Chapter 56]. There are perhaps 100 Aes Sedai nearby: about 50 outside in tents (the rebels' embassy, including Myrelle between them [ToM: Chapter 20]); the same inside, counting prisoner Reds and those few with Pevara. Some or most of the prisoner Reds may be off with Logain and some of both groups inside have been probably turned; however the rest can make circles with Androl's Asha'man, and this makes them not negligible.

5a) Who will alert Rand & co.?

The crucial fact will be for the Light to be informed of both critical situations (Caemlyn and the Black Tower) soon. There are various ways for this to happen.

i) First, I mentioned the communication ter'angreal stashed in the Royal Palace: perhaps some can communicate through the dome, and perhaps some of the channelers in the Royal Palace will find out how to use one of them. Most intriguingly, Setalle Anan is with Talmanes and Olver. Setalle in her former 'life' was Martine Janata, an Aes Sedai famous for her study of ter'angreal. She got burned out by one of her study objects, so she cannot channel any more, but perhaps she can understand what some of the communication ter'angreals do and give instuctions to another channeler to use one.
ii) Then, recall that Rand sent Naeff to the Black Tower to deliver a message to Logain and his followers, that Asha'man are men not weapons; per Rand's orders he'll Travel to somewhere close and then ride the rest of the way, then enter in disguise [ToM: Chapter 51]. We don't know how and if he'll be able to enter now that the Tower is closed and guarded, but just seeing the Tower closed and guarded will be enough for him to raise an alarm.
iii) Last, recall that Mat, Thom and Moiraine are waiting for Jur Grady's gateway every day at noon to get back [ToM: Chapter 53]. Jur Grady is likely with Perrin in Merrilor by now; so he'll bring them there at first. Moiraine then wants to go to Rand [ToM: Chapter 57] and she will find him there. Instead, Mat wants to go to Caemlyn [ToM: Chapter 57] to check with the Band and the Dragons. So, I think that soon he'll ask for a hop back to town. Jur Grady will not succeed, and having already dealt with Dreamspikes, he'll smell a rat and raise an alarm too.

A timing for that is impossible - plot-wise, whatever important will go on at Merrilor's gathering must have some time to develop. However, it still could be sooner than the Shadow hopes. Then, when both alarms are received, someone will go to Caemlyn.

5b) Who will go to Caemlyn?

Here we enter the ground of wild speculation. It is easier to say about two non-ta'veren:
- Elayne surely, with Birgitte & armies various.
- Logain very probably, as he needs to fulfil Min's vision of glory and the Black Tower and/or Caemlyn present a very good chance to earn it. Egwene's Dream of him mounting a black stone pedestal (the M'Hael prerogative) points in the same direction.

I expect that also some of the trio (Rand, Mat, Perrin) will go.

As usual, Rand might have something else to do (a world rests on his shoulders), so I wouldn't bet on it. He knows he must avoid a large confrontation before Shayol Ghul [ToM: Chapter 32], and he considers saving Maradon a mistake already in that respect. Only thing, Egwene's Dream about Logain (see above) also shows Rand's corpse or faked corpse (with Logain passing over it to climb the M'Hael stone), so maybe after all Rand will be involved, if only with the Black Tower. I don't expand on this point, you'll find many well-argued theories here and in other forums.

Mat? he wants to go to Caemlyn anyway, but he has another few small errands to see about that only he can do - saving the White Tower, putting some reason in Tuon's head, recovering and blowing the Horn, ... and I have the feeling that the Seanchan attack to the White Tower will happen (and be notified to Rand & co.) in the same moment. Then Egwene and Mat would be diverted there - by the way, the Seanchan will find a tough nut even if Egwene is out with some or many Aes Sedai. She'll have left behind a consistent part of the Tower Guard and/or Gareth Bryne's army; she knows the Seanchan have Travelling. Then, several or most Aes Sedai will still be in the Tower with more than 1000 novices and Accepted, some very strong, most trained to make circles and fight when they were with the rebels, the others having fought already in the first attack. The Seanchan field a bigger army - difficult to bring to bear in town, however - and some hundreds of battle-trained Damane, who cannot make circles, however, because of the a'dam. If Mat succeeds to stop the fight and bring Fortuona to reason, he may be saving both the White Tower and the Seanchan Army from reciprocal destruction. Then, why not, after all is said and done, he may even lead the Ever Victorious to Caemlyn...

Perrin? Yeah, he has also missions - maybe finding The Song, etc., but that's not immediate (would be a resolution move). He'll be "busy" also when Tenobia meets Davram Bashere, but we don't know if they are both at Merrilor, so that could happen later, too. Those two might also come with him to Caemlyn and die in battle, handing him the Broken Crown via Faile. On Perrin especially I'd bet, as he has experience with Dreamspikes and has a beautiful new Hammer that seems just the right instrument to smash them.

Or maybe two - or all three - Ta'veren will go? The possibilities are too many to count, alas. So, looking forward to RAFO about it!