Darkling, where to start?
1) Unless you can explain why the Royal Navy has even more SOLs in the area and why the available ships would be used properly there can be no great naval victory. Where is the POD where the sufficient RN force is suddenly declared inadequate and reinforced in a timely fashion?
You don't need more ships for the Royal Navy(although there easily could be given the right changes - that is sort of the point of this place after all).
In OTL Graves was so incompetent in his handling at the battle that only 12 of his 19 were brought against the French 24 and they still came out honours even.
Have Graves spontaneously combust (fall ill/slip on a wet deck etc) and Hood can win the day just by bringing all 19 ships against the disorganised French or even possibly going for a Nile annihilation of the enemy (which I have seen suggested although I'm unsure on).
Mahan presents a POD of his own in his study of sea power: Graves had sent out ships to gather intel but they had been captured due to incompetence on their part.
If they weren't and instead relayed the information, Mahan seems certain that Graves would have hidden his force in such a way as to fall upon (and take completely) the fleet coming from Newport under Barras.
Thus taking the French siege train and boosting British numbers beyond those of the French already in the bay, although even the prizes wouldn't be necessary since additional ships could now be brought from New York (the later proposed attack added 6 SoL) with the Newport fleet gone.
So pick any of those three.
2) Since you count Cornwallis as having 8000 men that means that the alleged 3500 Americans were sufficient to confine Clinton's 11,000 in New York.
Produce a counter figure then, I find the same figure in both "A few bloody noses" and "Rebels and Redcoats" whilst "The Long Fuse" puts forward only 2,000.
What do the sources you are using to base your conclusions off of say and what did you think the figure was when you began commenting?
They also weren't enough to confine Clinton, he simply was inactive because he didn't know what Washington was up to and when he finally realised he started to prepare for reinforcing Cornwallis.
In fact the Franco-American force at Yorktown would have outnumber Clinton AND Cornwalliis once those 3500 were joined. In a defensive plan there would indeed be thousands of troops available elsewhere.
Not quite, Washington took about 6,000 south(including the French), the French brought 3,500 from Hati and about the same from Newport.
A British interception of the Newport fleet reduces the French by 3,500.
The maximum the force outside Yorktown reached was 17,000, 3,500 of which were militia (R&R concludes in fact that the continental force was considerably lower as does the Wikipedia article and its sources but let us air on the side of the rebels) and aren't going to be of use outside Virginia.
Deduct the 3,500 captured French men and we arrive at 10,000, add in the 3,500 (or possibly lower) forces along the Hudson and we have 13,500 available to sit outside New York versus the British 19,000.
At Yorktown the balance would be 12,000 allies versus 8,000 Britsih rising to 15,000 once the planned 7,000 reinforcements arrive.
This also assumes that all regulars are withdrawn form Virginia and that department liquidated.
The French are also likely to want to return those troops to Haiti and possibly reoccupy Newport (should it still be available).
3) While fleeing to the boats Cornwallis will surely lose most of his supplies and artillery, assuming much of his army isn't overrun as well.
He has no need to flee, in fact the plan was to reinforce him.
Once the Britsih control the bay they can keep him supplied indefinably whilst the Franco-American force has no siege equipment and will quickly have an inferiority in numbers and position.
Further, what of British morale? The plan of three years, the first plan with an idea to actually win the war, has just collapsed after great expense, along with every post north of South Carolina, so how would an operation of unknown success and casualties and for far more limited goals possibly turn things around or prevent the collapse of Lord North's government?
Britsih morale will be rather high aftre the biggest Britsih naval victory for decades and the tipping of balance on teh seas into Englands favour.
Not to mention the capture of 3,500 French troops.
Add in the possibility of hitting West point or taking Newport and things don't look so gloomy.
I understand you point about a retreat being considered a blow but it is nowhere near the blow that the loss of 8,000 men was.
That was a military disaster of previously unknown heights and a simple dissatisfaction with the Southern campaign can come nowhere near to rivalling it.
I tried to use the idea once in a time line and it just wouldn't hold up - in the end I just had to have the army surrender as in OTL.
Add in a truly stunning naval victory possibly followed up with victories in North America (and certainly in the West indies which the French left devoid of ships to pull off Yorktown) and the Britsih are going to be delighted with these events and the failure/setback (because the forces may return there after Yorktown) in the South will get buried beneath the peeling bells ringing out for Hood (or the Duke of god knows where as he would be within 6 weeks of the battle).
Basically you see Lord North's government rallying because the cost from 1778 to 1781 may have been terrible, the waste great but at least part of the southern army survived.
No, you are glossing over and outright ignoring the positive effects and looking at the situation from the wrong angle.
you are assuming only a successful conclusion to the southern campaign can keep North in power whilst you should view the fact that it took a cataclysmic defeat unhallowed in the annuals of British history to bring him down.
If the British don't withdraw and simply wait the Americans out (in a situation where they are going to hurt more with disease etc than besieging up North and be far more vulnerable to having their supplies cut) then nobody in Britain will see this as a conclusion to the campaign anymore than they saw Cornwallis heading into Virginia to be that.
Really the Southern campaign was abandoned in March 81 yet we didn't see the fall of the government until a year later, I would suggest that it was the defeat of the army which was the vital blow.
In the interest of moving things further, would you agree that losing 8,000 troops was more of a blow than the recognition of the failure of Cornwallis in the south or is it your contention that it was the latter that caused the change in opinion not the former?
Assuming you agree it is the former then how much time do you think the non loss buys North.
How much additional time does the naval victory buy him?
What about west indies victories?
A Britsih repulsion of Washington's army?
A British destruction of west point (by moving the British forces north and attacking whilst the allies are in transit)?
The British retaking Newport?
The Britsih retaking Philidelphia?
The Britsih running Greene out of the South?
4) The Franco-American force at Yorktown of 17,000 was actually equal in size to the 7,000 under Cornwallis AND the 10,000 under Clinton.
I have 8,000 under Cornwallis and 11,000 under Clinton.
I also have 16,000 - 16,500 for the army at Yorktown in all three books but I too used 17,000 above.
In any case you need to account for the lost 3,500 Frenchmen.
Assuming a defensive posture in the north there will easily be American or French forces for the Deep South.
As I have demonstrated you have to take into account the lost 3,500 Frenchmen, the 2,000 (minimum) state bound militia, the 3,500 French that will be wanted back in Haiti (they were only released upon the condition of a Spanish fleet guarding Haiti n return -- a fleet which will be so much dog meat once Hood heads south) although the French will have problems arranging transport, the French desire to hang onto Newport and the French disinterest in running about the south.
You also (and you seem to have neglected this despite previous mention) need to address why in OTL Washington took his forces back north to guard Clinton in OTL even when he had 8,000 less men.
Further, as New England and the Middle Atlantic is in the hands of the militias loyal to the Continental Congress the British ability to hold land other than South Carolina and Georgia is doubtful except by losing men in battle and many men to hold any position.
Initially, yes but we are getting ahead of ourselves.
The Britsih can build up a network if they hold onto somewhere long enough and the civilian populace can have its faith in the cause shattered.
Especially by a French withdrawal etc.
In any case this is a retreat form your earlier position which essentially held that the British wouldn't make any gains from such a situation(talk of forces securing the great lakes on the basis that the US would gain those despite Yorktown), if they can hold South Carolina and Georgia until the peace then they will have something to gain there, especially since at worst the Britsih would probably be looking at the French backed uti possidetis based peace (which they had already been pushing for a year - showing they weren't exactly enthused with the shape of events).
Also, if Clinton in unwilling to attack with an advantage of nearly three to one why would he or Cornwallis consider attacking a force of nearly equal size, stronger if Washington puts everything on the spot.
Well despite the early problems with your numbers I pointed out above (mainly due to the breakdown of forces which you probably weren't aware off without looking unto the matter closely) I pointed out that Clinton didn't attack because he had little time between Washington leaving (he made a feint to keep Clinton pinned at first) and his preparations to leave to help Cornwallis.,
Clinton's thoughts were revolving around Yorktown (whether to chase Washington or said aid via ships) not attacking Westpoint.
Obviously matters change once Yorktown is resolved.
Back when the British held Newport, New York AND Philadelphia the manpower needed for all three left practically nothing for further operations and added the risk of Washington(before France arrived) falling on one force.
Well back then the continental army was a little short of three times the size it was by this point so that comparison doesn't really work.
What happened at this time should be a more clear yardstick - the Britsih were able to be safe in NY and match around Virginia with impunity whilst sitting in forts in the South.
Only the addition of a considerable number of French troops and ships allowed that situation to be exploited and even then it required West point to be left dangerously open to attack.
However I would also question whether there really was any danger of Washington falling on any of the forces, Newport was secure until French entry, New York didn't have much pinning it down (and operations were possible, ill fated as Saratoga was the British did it and they were also able to send forces up the Hudson although Clinton's timidity limited that operation it wasn't because there were seriously to few troops) and the British could sit at Philidelphia safely.
Of course this is of little relevance because the situation had change for both sides.
5) The British previously abandoned Newport on the grounds that it was too costly to hold, requiring no less than 6,000 men at the time of withdrawal, effectively destroying British mobility when added to NYC's needs.
Not quite, there were fears for Newport safety due to the French naval threat and it was finally evacuated when Clinton learnt the French were heading north form the West Indies.
In any case it needn't be that costly if one has naval dominance, although you could certainly make a case that there were better places to spend the troops.
Letting the French have it and draining off 4,000 or so of their troops to act as a garrison wouldn't be harmful to the British cause.
To retake the city, after losses naturally, only reverts to the very strategic weakness which the British correctly abandoned without any relevant gain.
Well the British had it because it was the bets harbour about, this is exactly the reason the French wanted it and made it their base of operations.
6) Stating that failing to release POWs in a timely fashion is 'not quite killing them' is absurd.
Again they weren't POW's, they were people who were transiting under a truce back to Britain.
And when you say timely fashion, you mean five years too late(except for exchanges).
I did point this out, if you aren't familiar with the incident in question just ask instead of just repeating yourself.
Comparing it to a sudden assault under the white flag is more so,
Well if you understand the incident you wouldn't be quite so incensed, although never did I say they were equivalent only that the US had shown dishonour in that exact field.
not that I find Cornwallis remotely capable of such dishonorable behavior.
Nor do I, he was quite a good sort by all accounts or his actions in India (where they still look after his statue showing he must have some esteem over there) and in Ireland where he was hated by the Ascendency (the mark of all right thinking individual).
So now we have the war as it was in the Deep South, probably with more men on both sides, a little pawing around western Connecticut or northeastern New Jersey, a worsening problem for the British taxpayer, a crumbling government and the opposition noting that after eight years, tens of thousands of casualties and terrifying costs George III is the proud owner of Georgia, New York City, parts of South Carolina and possibly Newport while France, Spain, Holland, Portugal, Prussia, Denmark, Sweden, the Ottoman Empire, Russia and more are all offering various degrees of insult or outright war. Where is the light at the end of the tunnel for England?
The largest naval victory in decades(potentially ever), the French cast out of the Caribbean which is thrown open to British ravages, a rebel army racked with mutiny and declining popular support, a failing interest in France, a worsening bank balance for the enemy and the possibility of a French separate peace.
That is the light at the end of the tunnel, although since the war continued for another year and a half anyway the British can use that time to get closer to the light.
It may well be that the British accept a peace which recognises the facts on the ground which is what I outlined earlier but that would put them ahead of OTL (in the peace terms at any rate).
Should the French come to the table with a sweet heart offer after naval defeats and possible lost Caribbean holdings and the British take it, well then the rebellion is there to be crushed, the moral blow for the rebels would be huge, their forces greatly outnumbered and unfinanced and the British would be free to deploy some of those 150,000 men under arms beyond the 23,000 or so that were deployed at this point.
the game was still there to be won at this late stage, after all Washington thought so and he was he was trying to talk up his side by saying they could still win it.