Why did Varys kill Grand Maester Pycelle?

[zandru]

1 hour ago, Lord Varys said:

Mace and Randyll know what Cersei tried to do to both Loras and Margaery (trying to get both of them killed).

Wasn't Pycelle a witness, alleging that he supplied Margaery with moon tea - thus incriminating her of unchaste acts? Pycelle might have been lying to aid the Lannisters, as he's wont to do - but if he's dead, he can never publicly recant.

[BalerionTheCat]

Pycelle knew something about Varys:

There are things I might tell you of that eunuch that would chill your blood.

But he was the Grand Maester in the time of baby Aegon. A maester may see things others don't see. Luwin was able to recognize the burned body was not Bran:

The legs, I could tell ... the clothes fit, but the muscles in his legs ... poor lad ...

With reason or not, Varys would take no risk.

[Lord Varys]

2 hours ago, rotting sea cow said:

What makes you think that Harys will retain his position as Master of Coin? The Tyrells have several candidates and Mace is the hand.

Well, some landed knight who was formerly the Master of Coin would also not have the right to see the imprisoned Queen Dowager without the Hand giving his leave. But then, we know that Swyft is going to end up at Braavos, strongly suggesting that he will go there as Tommen's Master of Coin by the command of Mace, as the Small Council already agreed he should. But he is not going there under the command of Cersei - as implied by 'Mercy' but under the command of Mace.

1 hour ago, BricksAndSparrows said:

I'm sure this has been speculated at already (I haven't read the entire thread,) but maybe Pycelle's apartment's were the easiest place to infiltrate. That, and (I know this has been suggested already,) Pycelle gives good counsel. Not to mention, Varys might also have some inclination about just who will be replacing Pycelle. 

I've suggested that. Kevan (and Tommen and Cersei) are safe from Varys and his little birds in Maegor's Holdfast. There is only one secret escape tunnel there, in the royal apartments, allowing the king to escape if he is besieged in Maegor's. But those are unconnected to the other tunnels. Maegor did not want to enable his spies to spy on and/or kill himself.

Pycelle's certainly is one of the places Kevan was likely to visit without a (large) retinue of guards. If Kevan had arrived with just a few guards Varys most likely would have killed those, too, and if he had brought too many men for some reason he would have just stayed in the tunnel.

1 hour ago, zandru said:

Wasn't Pycelle a witness, alleging that he supplied Margaery with moon tea - thus incriminating her of unchaste acts? Pycelle might have been lying to aid the Lannisters, as he's wont to do - but if he's dead, he can never publicly recant.

Pycelle confessed that Margaery had asked him for (and gotten) moon tea from him, but when Cersei interrogates him about that she cuts him off when he wants elaborate on the details. He is trying to something, but when he reaches 'for' (it is never clear what he intended to say) Cersei cuts him off, saying she knows what moon tea is for. But it may be that Pycelle wanted to say for whom the moon tea Margaery was asking him for actually was. It is never said that she intended to use it herself. It might be that it was for one of her cousins, the one who is engaged to marry someone.

But his public involvement in Cersei's campaign against Margaery clearly caused the ire of Mace, and Pycelle most likely is correct to fear for his life. The chances that Mace and Tarly actually intend to allow Cersei and her people to get away with what they tried to do to Margaery is not all that likely.

[Lady Blizzardborn]

Pycelle may or may not be able to identify Aegon but that's beside the point.

The main reasons for killing Pycelle are 1) he and Kevan are doing too good a job restoring some semblance of order to the realm and 2) to bust up the alliance between the Lannisters and Tyrells.

Because Pycelle is the star witness against Margaery, when it's found out that he's dead Cersei will immediately think the Tyrell's did it. Also, because he was the star witness against Margaery he might well have been able to prove her innocence. Cersei never let him finish saying what Margaery wanted the moon tea for, and if he had finished that statement during the trial, Margaery might well have gone free and stayed Tommen's queen...thus the Tyrell-Lannister alliance would have continued even as Margaery was much more careful about watching her back around Goodmommy Dearest.

[zandru]

7 minutes ago, Lady Blizzardborn said:

Because Pycelle is the star witness against Margaery ...

Good concise summary! We the readers know, from Cersei's POV, that all the allegations against Queen Margaery were totally fabricated, nonsense from Cersei's addled brain - basically, projections of what dowager former queen Cersei was herself doing, or what she planned. (Frankly, there's a lot of that going around, even to the present day - but I digress.)

Pycelle was heavily Lannister-biased, but given the choice between wackadoo Cersei and good old level-headed Kevan, he might very well have stuck with the reality-based lion. And, as far as Varys is concerned, this could put a halt to Cersei's crazy tearing down of a functioning government. Young Griff / long lost Aegon will do best if the rulers of King's Landing are totally dysfunctional and chaos reigns. So both Kevan and Pycelle had to go.

[Humble Maester]

Personally I think it was for much the same reasons for which he killed Kevan. Pycelle would had been one of the few people willing and capable in working to strengthen the realm. This is a point of view anyone who subscribes to the "Pycelle's only mancrush was Tywin" theory would disagree, but I do believe that in his tenure as Grand Maester he always tried to put the interests of the realm first as he saw them (unlike Varys), even if his opportunities were fairly limited most of the time due to his power as a mere advisor.

[LordToo-Fat-to-Sit-a-Horse]

When the bodies of Kevan and Pycelle are found the next morining, Mace will take the regency and most of the small council.

Pycelle was a key witness against his daughter, having publicly accuse her of drinking moon tea.

 

Him dying makes the tyrells look guilty. Killing both Pycelle and Kevan looks like a power play to take the regency.

 

[Ralphis Baratheon]

Pycelle is known as a Lannister man so by killing him along with Varys' main target Kevan it looks like "someone" is killing off Lannisters and their supporters. Varys led Tyrion into killing Tywin so Cersei will think it's either Tyrion hiding in the walls or the Tyrells or somehow both.

[elder brother jonothor dar]

There will be a funeral and a trail,

 

Once Cersei is found innocent one way or another she will be free of the faith, but she is the mother of the king and as soon as she can get her claws back into the familyless Tommen she will regain the regency.

 

The boy has lost his father uncle (twice) sister brother grandfather wife brother in law mother great uncle and various other family members in quick succession.  He will want his mother/wife back asap and I put my money on Cersei winning the race to be first into his open arms

[rotting sea cow]

14 hours ago, Lord Varys said:

Well, some landed knight who was formerly the Master of Coin would also not have the right to see the imprisoned Queen Dowager without the Hand giving his leave. But then, we know that Swyft is going to end up at Braavos, strongly suggesting that he will go there as Tommen's Master of Coin by the command of Mace, as the Small Council already agreed he should. But he is not going there under the command of Cersei - as implied by 'Mercy' but under the command of Mace.

So, you are willing to accept that Swyft will remain in the Small Council as the Master of Coin, but not that Cersei is back in power as implied by the same chapter?

I mean, I understand you. The most logical  path is what you describe with the Tyrells full in power. However we have that tidbit of information from Mercy, which is the best we have until TWOW is published, as illogical it may sound. Our scenarios need to consider that, until the God of the ASOIAF Universe (aka GRRM) decides otherwise. This includes that Cersei is back in power, somehow.

And it makes sense. Cersei is a PoV who is not yet at the end of her arc and the Tyrells are supporting cast. They are not heroes nor villains. Even their characterization is less prominent than important non-PoV characters like Stannis, Tywin, Varys or Littlefinger, who are key part of the story.

Finally, to make it truth the "cloth dragon swayed on poles amidst a cheering crowd", i.e. that the people of KL will welcome Aegon with all their hearths, we need that whoever was in the IT must have been despised. The Tyrells are loved.

 

[Lord Varys]

52 minutes ago, rotting sea cow said:

So, you are willing to accept that Swyft will remain in the Small Council as the Master of Coin, but not that Cersei is back in power as implied by the same chapter?

Yeah. The history of the Mercy-chapter reveals that it is a very old chapter, the first Arya chapter George wrote to continue her story after the five year gap (just as Alayne 1 is). Those chapters aren't finished yet. There are still inconsistencies there. Raff and his buddy have no memory of Cersei's walk or the various crises Westeros is in, and Swyft doesn't even give the impression his son-in-law was brutally murdered. He enjoys himself in Braavos.

That doesn't make any sense. George went out of his way to allow Arya to murder Raff the way he originally envisioned it by reintroducing him in AFfC - Jaime finds him at Harrenhal, sends him to Maidenpool with Wylis Manderly, and then he arrives in KL in the army of Randyll Tarly, now being set up to be hired as a guardsman by Harys Swyft - but this doesn't mean the chapter fits into TWoW as it stands now in the shape it is right now.

Just as Alayne 1 might need some cleanup. Robert seems to be far too old in this chapter in comparison to the older chapters, and Sansa far too content with her role as Littlefinger's daughter. We left her when Littlefinger told her they were essentially murdering her cousin and setting her up to marry his heir. Does this not concern her? In Alayne 1 it doesn't, most likely because such a conversation didn't only take place after this chapter was written.

52 minutes ago, rotting sea cow said:

I mean, I understand you. The most logical  path is what you describe with the Tyrells full in power. However we have that tidbit of information from Mercy, which is the best we have until TWOW is published, as illogical it may sound. Our scenarios need to consider that, until the God of the ASOIAF Universe (aka GRRM) decides otherwise. This includes that Cersei is back in power, somehow.

It is actually not confirmed that the queen they are talking about is Cersei. It could also be Margaery (or somebody else entirely). And the whole thing is clearly at odds with Arianne 2. There it is said that a Tyrell army is marching or will march against Storm's End, something that is not likely to happen unless Mace and/or Tarly remain in charge of things in KL. If they did not then the Tyrell armies would have no reason to actually defend King Tommen. They could instead simply march home to help defend the Reach against the Ironborn.

If there was bloody or bloodless coup and Cersei ended up in charge again that is most likely what would happen.

52 minutes ago, rotting sea cow said:

And it makes sense. Cersei is a PoV who is not yet at the end of her arc and the Tyrells are supporting cast. They are not heroes nor villains. Even their characterization is less prominent than important non-PoV characters like Stannis, Tywin, Varys or Littlefinger, who are key part of the story.

That is true, but if Cersei ended up in power again she is not likely to survive Aegon's arrival. If she was retaking the Regency or setting herself up as the real ruler behind Tommen's throne somehow Varys would not allow her to get away. She would be one of Aegon's prices upon his arrival. But I don't think she is going to die soon.

52 minutes ago, rotting sea cow said:

Finally, to make it truth the "cloth dragon swayed on poles amidst a cheering crowd", i.e. that the people of KL will welcome Aegon with all their hearths, we need that whoever was in the IT must have been despised. The Tyrells are loved.

That might help them either switch to Aegon's side in due time. There is not likely going to be a battle in or even for KL. That would Aegon has to take his throne over a lot of dead bodies, possibly even a lot of Kingslanders. That would not only not look good but make it rather unlikely he would ever be cheered. There might be some pitched battle in the Stormlands but even that shouldn't be all that bloody. But if Aegon still wins a decisive victory and has many of the Reach men declaring for him and joining him in the aftermath this could have a ripple effect that leads to the Reach men in the capital to declare for him, too, meaning that he will find open gates and a welcoming city upon his arrival.

It is not that likely that George is going to slow down this story. We'll have Dorne joining Aegon, some Stormlords and Reach lords joining Aegon at Storm's End, some pitched battle at Storm's End (if that is necessary) and then quick march to KL to take possession of the Iron Throne.

[BRANDON GREYSTARK]

Why not , he was a Lannister loyalist , and his death by arrow ,which would look like Tyrion had killed him , would drive Cercei crazy .

[BricksAndSparrows]

18 hours ago, Lord Varys said:

Pycelle's certainly is one of the places Kevan was likely to visit without a (large) retinue of guards. If Kevan had arrived with just a few guards Varys most likely would have killed those, too, and if he had brought too many men for some reason he would have just stayed in the tunnel.

Sure. Sounds good to me.

Do we have any inkling who might be replacing Pycelle as Grand Maester at court/ on the Small Council?

That may well matter here as well.

[Lord Varys]

Just now, BricksAndSparrows said:

Sure. Sounds good to me.

Do we have any inkling who might be replacing Pycelle as Grand Maester at court/ on the Small Council?

That may well matter here as well.

Varys claims that Maester Gormon (Tyrell), one of Mace's uncles (who right now is also filling in for Archmaester Walgrave), was the one the Citadel chose to replace Pycelle with after Tyrion had him stripped of his office. It is not all that unlikely that he is also going to be the new Grand Maester now if we assume that Varys had accurate information. House Tyrell has a lot of power in Oldtown, not just in the Reach at large. Mace is married to Lord Leyton's daughter and Mace's other uncle, Ser Moryn Tyrell, is Lord Commander of the City Watch of Oldtown.

The Citadel doesn't exist in a vacuum. If Gormon wants to be Grand Maester he will be Grand Maester.

[BricksAndSparrows]

4 minutes ago, Lord Varys said:

Varys claims that Maester Gormon (Tyrell), one of Mace's uncles (who right now is also filling in for Archmaester Walgrave), was the one the Citadel chose to replace Pycelle with after Tyrion had him stripped of his office. It is not all that unlikely that he is also going to be the new Grand Maester now if we assume that Varys had accurate information. House Tyrell has a lot of power in Oldtown, not just in the Reach at large. Mace is married to Lord Leyton's daughter and Mace's other uncle, Ser Moryn Tyrell, is Lord Commander of the City Watch of Oldtown.

The Citadel doesn't exist in a vacuum. If Gormon wants to be Grand Maester he will be Grand Maester.

I'm sure Cersei will acquiesce to the Citadel's wise judgement in that matter......

Come to think of it, that may be another reason why Pycelle's death is beneficial to Vary's (if not one of the Eunuch's motivations for killing him.)

If Cersei decides to stamp her foot and not accept the Citadel's decision, it would just sow further discord between Cersei and another powerful (would-be) ally.

[Lord Varys]

2 minutes ago, BricksAndSparrows said:

I'm sure Cersei will acquiesce to the Citadel's wise judgement in that matter......

Come to think of it, that may be another reason why Pycelle's death is beneficial to Vary's (if not one of the Eunuch's motivations for killing him.)

If Cersei decides to stamp her foot and not accept the Citadel's decision, it would just sow further discord between Cersei and another powerful (would-be) ally.

Nobody is going to ask Cersei for her opinion anyway. She has no role in the government of the Realm.

[BricksAndSparrows]

28 minutes ago, Lord Varys said:

Nobody is going to ask Cersei for her opinion anyway. She has no role in the government of the Realm.

I doubt Cersei has lost her taste for power and control and her ineptitudes represent the biggest internal threat to Tommen's reign. I think this must have occurred to Varys when he decided to kill Kevan, who was a significant obstacle for the Queen dowager. With her uncle gone, I suspect Cersei will try to shove her way back into the halls of power.

To try and tie this back in (I know the thread isn't "what will that rascally queen do next?") I'm thinking this is why Vary's did his killing: to clear a path for Cersei to come in and screw everything back up, again. 

[Lord Varys]

Just now, BricksAndSparrows said:

I doubt Cersei has lost her taste for power and control and her ineptitudes represent the biggest internal threat to Tommen's reign. I think this must have occurred to Varys when he decided to kill Kevan, who was a significant obstacle for the Queen dowager. With her uncle gone, I suspect Cersei will try to shove her way back into the halls of power.

You would have to explain how this is supposed to work to convince me. She certainly isn't done as a character or player but she is not going to run Tommen's government.

Just now, BricksAndSparrows said:

To try and tie this back in (I know the thread isn't "what will that rascally queen do next?") I'm thinking this is why Vary's did his killing: to clear a path for Cersei to come in and screw everything back up, again. 

Varys killed Kevan because he was ruining all the queen's good work - which means he was doing his best to try to correct Cersei's mistakes which were ruining the government of Tommen and undoing all the victories Tywin won and the alliances he made. He never says he wants Cersei back in charge. A Cersei back in charge would mean she had to kill all her enemies. Neither Mace nor the High Septon is ever going to allow Cersei to seize power again while they are still alive.

What Varys wants is that the three factions in KL - the Faith, the Lannisters, and the Tyrells - don't work together to try to defeat Aegon but rather that they use as many resources as they can to fight each other rather than build up a united front against Aegon. If they did that, and if they acted quickly and decisively, they would still have a good chance to make Aegon nothing but an odd footnote in the history of Westeros. But with Kevan dead that's not going to happen.

Cersei will never work with Mace, and Mace is very unlikely to consider working with Cersei. And neither of them - especially not Tarly - has the good sense Kevan had to understand that the Faith should better not be unduly provoked.

[rotting sea cow]

On 5/16/2017 at 4:46 PM, Lord Varys said:

Yeah. The history of the Mercy-chapter reveals that it is a very old chapter, the first Arya chapter George wrote to continue her story after the five year gap (just as Alayne 1 is). Those chapters aren't finished yet.

Of course there are not, but still they are the best we have. Many things can change and many other will not. Until that time we have to soup with whatever meager meal we are given.

On 5/16/2017 at 4:46 PM, Lord Varys said:

There are still inconsistencies there. Raff and his buddy have no memory of Cersei's walk or the various crises Westeros is in, and Swyft doesn't even give the impression his son-in-law was brutally murdered. He enjoys himself in Braavos.

That doesn't make any sense. George went out of his way to allow Arya to murder Raff the way he originally envisioned it by reintroducing him in AFfC - Jaime finds him at Harrenhal, sends him to Maidenpool with Wylis Manderly, and then he arrives in KL in the army of Randyll Tarly, now being set up to be hired as a guardsman by Harys Swyft - but this doesn't mean the chapter fits into TWoW as it stands now in the shape it is right now.

There are a lot of inconsistencies throughout the books. Don't look with suspicion  at every detail, otherwise you will end like Preston Jacobs

On 5/16/2017 at 4:46 PM, Lord Varys said:

It is actually not confirmed that the queen they are talking about is Cersei. It could also be Margaery (or somebody else entirely).

Yeah, it could be "the hand will have his head", a simple line, but as long as it doesn't happen I will still assume that it refers to the queen.

On 5/16/2017 at 4:46 PM, Lord Varys said:

And the whole thing is clearly at odds with Arianne 2. There it is said that a Tyrell army is marching or will march against Storm's End, something that is not likely to happen unless Mace and/or Tarly remain in charge of things in KL. If they did not then the Tyrell armies would have no reason to actually defend King Tommen. They could instead simply march home to help defend the Reach against the Ironborn.

The timelines are always complex here. Mercy seems to be to further inside the book than Arianne's chapters, so there is no necessarily a contradiction.

On 5/16/2017 at 4:46 PM, Lord Varys said:

That is true, but if Cersei ended up in power again she is not likely to survive Aegon's arrival. If she was retaking the Regency or setting herself up as the real ruler behind Tommen's throne somehow Varys would not allow her to get away. She would be one of Aegon's prices upon his arrival. But I don't think she is going to die soon.

We would need to try to imagine here what would be the following course of action for Varys. If the Tyrells control the IT, they have no reason to switch sides, so after Kevan & Pycelle, poor sweet Tommen should follow as the Tyrell power derives from him, leaving a queen Maergery kingless. She is the next best thing for Aegon after Dany, bringing the power of the Reach (it is very likely than Varys is also underestimating the danger of Euron giving the Redwyne's victory for granted).

Now, Aegon has a big problem. How does he make the lords of the realm, many of them tired of war, to believe he is the real deal? Any Targaryen loyalist has been waiting for Dany and suddenly a walking dead shows up. The key here is Dorne, if "his uncle" vouches for him, people will most likely feel more confident, specially if the situation at KL gets very bad. To get Dorne, team Aegon needs to convince Arianne. Will they? What will Arianne demand in change? Will she say "marry me and Dorne is yours"? JonCon will oppose, but if for some reason they get trapped at Storm's End, they might reconsider. She is right there, Maergery is not.

Now if Tommen were to die, the heir is Myrcella. Will the Sand Snakes (with the support of the Faith) try to pull a Queenmaker 2.0 against the Tyrells? Or just the sight of Robert Strong will send them in rage? They don't know that Arianne is at SE.

There are a lot of actors and uncertainties in this subplot, but I believe that having Cersei (brutally) back in power will help Aegon cause. A realm happy with the Tyrell governance will make everything much more difficult for Aegon.

 

[Lord Varys]

3 hours ago, rotting sea cow said:

Of course there are not, but still they are the best we have. Many things can change and many other will not. Until that time we have to soup with whatever meager meal we are given.

We actually don't. We don't have to read sample chapters or read reports from readings.

And we have to keep in mind that everything not actually published isn't actually canon. It is still subject to change. Alayne 1 contains a lot of typographic errors that are most definitely being correctly in the final version of the chapter.

And unlike Arianne 1 + 2, Theon 1, and the chapters covering the Battle of Fire Mercy and Alayne 1 weren't essentially finished already for ADwD, being moved to TWoW only shortly before publication.

3 hours ago, rotting sea cow said:

There are a lot of inconsistencies throughout the books. Don't look with suspicion  at every detail, otherwise you will end like Preston Jacobs.

Most certainly not. I look at inconsistencies in unfinished chapters, not so much in published material.

3 hours ago, rotting sea cow said:

The timelines are always complex here. Mercy seems to be to further inside the book than Arianne's chapters, so there is no necessarily a contradiction.

I'd not speculate on that with the flimsy evidence we have. Arianne 1-3 were originally supposed to take place before the Epilogue of ADwD. The decision to shuffle those chapters to TWoW changed the time line a lot. Mercy could easily enough take place before Arianne 2 or 3. Perhaps even before Cersei 1 or at least Cersei 2. It is Arya 1, and it is not all that likely that the first Arya chapter is going to come around page 200 or 300 of TWoW.

3 hours ago, rotting sea cow said:

We would need to try to imagine here what would be the following course of action for Varys. If the Tyrells control the IT, they have no reason to switch sides, so after Kevan & Pycelle, poor sweet Tommen should follow as the Tyrell power derives from him, leaving a queen Maergery kingless. She is the next best thing for Aegon after Dany, bringing the power of the Reach (it is very likely than Varys is also underestimating the danger of Euron giving the Redwyne's victory for granted).

Nothing indicates Mace will be able to keep a firm grasp on power. There are obvious that he and especially Tarly won't settle things with the Faith peacefully now that Kevan is gone. Tarly pushed to use violence against the sparrows back in the Epilogue. Cersei won't support him, and while she won't be able to do anything directly against him a public breakup of the Lannister-Tyrell alliance is not going to help Mace.

And then there are the military matters. If Mace doesn't win a decisive victory against the Golden Company he is done. 

Margaery is soiled goods now, and her fate is as of yet undecided. If Mace and Tarly turned against the Faith she might be declared guilty. If they go through with her trial she might also be declared guilty due to some unforeseen circumstances.

3 hours ago, rotting sea cow said:

Now, Aegon has a big problem. How does he make the lords of the realm, many of them tired of war, to believe he is the real deal? Any Targaryen loyalist has been waiting for Dany and suddenly a walking dead shows up. The key here is Dorne, if "his uncle" vouches for him, people will most likely feel more confident, specially if the situation at KL gets very bad. To get Dorne, team Aegon needs to convince Arianne. Will they? What will Arianne demand in change? Will she say "marry me and Dorne is yours"? JonCon will oppose, but if for some reason they get trapped at Storm's End, they might reconsider. She is right there, Maergery is not.

They need Dorne. Desperately need Dorne. They will give them everything Arianne demands. And if news about Daenerys' marriage, alleged death, etc. have arrived by the time this question comes up nobody in Aegon's camp will oppose such a marriage. But even if they did, Aegon will decide who he is going to marry, not Connington. Aegon will make all the important calls in his campaign now, not the men around him. He has made that pretty clear.

3 hours ago, rotting sea cow said:

Now if Tommen were to die, the heir is Myrcella. Will the Sand Snakes (with the support of the Faith) try to pull a Queenmaker 2.0 against the Tyrells? Or just the sight of Robert Strong will send them in rage? They don't know that Arianne is at SE.

As of yet they are not even in KL. Nym and Myrcella might never reach the place, getting caught by the Golden Company instead. They also have pretty few men in a city full of Tyrells and sparrows. It will be pretty hard to do anything openly violent in there. And while there is a good chance that Tyene might acquire some influence in the Great Sept this would have to be a longterm game. The High Septon is not going to listen to a pretty face he knows for, well, five minutes or so.

What Tyene could do is push the Faith into Aegon's direction if she learns that Dorne has joined him. But I'm not sure the High Septon needs much nudging in that direction.

3 hours ago, rotting sea cow said:

There are a lot of actors and uncertainties in this subplot, but I believe that having Cersei (brutally) back in power will help Aegon cause. A realm happy with the Tyrell governance will make everything much more difficult for Aegon.

Cersei can't get back into power. She has no men to rule or enforce her will.

The point of Varys' plan is to pitch the Tyrells, Cersei, the Faith, and the Dornishmen (should they arrive in the city) all against each other so that they are not going to fight against Aegon. That's the plan.

Mace will only be essentially the guy in charge in the city while he has army still with him. If he sends too many against Aegon (and stays in the city) he might lose control. If he and Tarly attack the Great Sept he might face riots of the same sort the Targaryens faced during the Dance, never mind the army in the city. If there is open violence between the Lannister and Tyrell men in the Red Keep, both factions might lose control over the city, etc.