The calculations are conceived in Valenwood by the last of the Ayleids. When they find Tiber Septim ascended to deity, they ask at once how the disaster may be counteracted. They seek merely a weapon against the ascendant usurpation of Men. What they find is the answer to the problem of problems. What they find is the truth that will break the great deception of Lorkhan.
They manage to break the power of Falinesti with no one the wiser. Two generations – three centuries – pass before the broader stratagem can be put into practice. But it may be said with confidence that this is only a delay. Their last vengeance against the Slave-Queen – the split-second asynchronicity the greatest latter-day Ayleid scholar placed, in secrecy, upon the Red Diamond – has already eliminated one line of Dragonborn kings. It will do the same for the Septims.
When they find that a band of assassins stands ready to eliminate the last four, the last favor of maddened Auri-El on the vermin, they act. They call, in secret, on the likeliest mer they can find: all Altmer of the Summerset Isles, for there they are found in quantity, and positions of power, to make swathes of the map after their image. A few are told all. More, not to be trusted so freely, are simply spurred to conquest such as the Ayleids themselves once enjoyed.
It will all come to the same end.
There are two hitches. First, they had discounted the extent of Dagon's ambition, and that becomes a near thing. Second, there remains a Dragonborn line, and it does not end with Martin Septim. It is certain, at least, that the Seventh Champion of Cyrodiil is not the progenitor. Once, at an early stage, the Thalmor are sure they have found the missing thread, but in the chaos of the Stormcrown Interregnum – hardly an interregnum at all, but a great confusion in the historical eyeblink that it is – the line vanishes once more into shadow.
But the next two centuries are profitable: they have chosen their agents well. By the stratagems of the Thalmor, the Crystal Tower and the Red Mountain are broken, and Valenwood comes out from under the dominion of Man for the first time in nearly five hundred years. The White-Gold Tower may be credited to the Ayleids directly. The Snow Tower – a mere fluctuation in the fabric of time, no machination at all, but it will serve its turn. The Thalmor have proven apt if not complete conquerors, and the strength of Talos is ebbing with every worshipper that dies. The methods of execution have, likely, some Dwemer influence, but the principle is absolutely Ayleid, and works to perfection: those who survive are usually too numbed by terror to continue.
Only the Adamantine Tower remains in full fastness. And after the last Dragonborn is swallowed up by Hermaeus Mora, the last pieces fall into place readily enough.
Cyrodiil and Skyrim, weakened by the rebellion of Ulfric Stormcloak and the assassination of Titus Mede, drop into the Aldmeri Dominion's hand like a swollen plum ready to drop from the stem. Their spies have been swarming through the territories unhindered for decades, after all, tasked with more than simply hunting out heretics – though that has proved reason enough for most of these humans to refrain from impeding their movements. The Ayleids never paused to mark which humans had actually won the war in Skyrim. The only significance was in the bloodshed, in making certain that the thirty years since the first attempt did not allow a new full flower of fighting men to greet them.
With the last remnants of Empire, Talos, too, is extinguished. Every image of Talos is broken – the man, the dragon, the hammer. Every Dragon Banner is burned. The diamond on the doors of the Imperial City is chiseled out. The executions continue, of course – for who would have it any other way? – but, from a cosmological perspective, they have become superfluous. And while the Ayleids know full well that Talos is no longer the only problem, that the last Septim has followed the first into deity, the forgetful humans never learned it. As Lorkhan himself has proven, a god without worshippers is no obstacle at all, and the shrine is the sole seat of worship.
Politically, High Rock is the softer means of approach to the main goal. But the emissaries and generals of the Thalmor, without whom the Ayleids and those who have learned their wisdom are powerless, wish instead to exact revenge on Hammerfell for its defiance. Plans can, fortunately, be drawn up accordingly. First hired corsairs harry Hammerfell's ships to the west. Then the Thalmor, having restored the old knowledge of the Aldmeri warship, begin their true naval invasion, and at the same time beset Hammerfell from the conquered east.
All the while, the main front is far from any shore. A long-forgotten portal leads directly to Hammerfell from the heart of Valenwood.
A good many of the Ayleid masters pass through this portal. They have long been content to survey many of the developments from afar, or in Valenwood itself, but this is the last stage. This, they wish to see in the flesh.
It is good fortune that they do. The stone of the Adamantine Tower, vaulted in that Tower itself, is safeguarded not only by a complex and deadly key but by a ripple in Time itself – a split-second asynchronicity, a mirror to the curse laid on the Red Diamond, operating to favor rather than thwart the binding of Auri-El. Only the Ayleids possess the knowledge to reverse it and expose the stone. The only precaution is to ensure the Redguards are sufficiently occupied elsewhere that they do not come in force to the northeastern shore. An easy task, and soon accomplished.
In the final victory, after the Adamantine Tower falls – but there is no "after". "After" has become a word without meaning. Indeed, it is difficult to use words at all without attaching the false implication of time.
Nonetheless, here is what comes.