The change of hands in Gori was a heavy blow to the Tbilisi court.
Facing such dire news and the relentless advance of the Bosporus Army, the court's war hawks finally began to gain the upper hand.
Although the Royal Family still hadn't given up on the idea of peace talks, at least they wouldn't argue over war or peace to the point of completely neglecting their defenses as they had before.
However, Manuel did not give Georgia time to regroup.
Less than half a month after occupying Gori, he led his grand army eastward, advancing rapidly and splitting his forces to successively conquer the three important towns of Kaspi, Tsalka, and Dmanisi.
Afterward, having arranged for garrisons, he gathered over six thousand elite troops skilled in mountain warfare, preparing to completely shatter the last line of defense west of Tbilisi—Mtskheta.
At this time, although all the generals and lords were celebrating the continuous great victories of the Autocratic State, Manuel became even more solemn.
The Georgians were not fools; having been pushed to such a point, it was impossible for them to still harbor illusions of peace as before; at the very least, they would first try to defend their capital.
In other words, whether he could conquer a strategically important town like Mtskheta, which guarded the capital, was now the top priority.
If he was blocked by the Georgians' likely forthcoming resolute defense, then there was an eighty percent chance that the objectives of his current campaign in Georgia would be questionable.
To conquer this formidable city, Manuel, after discussing with his generals and lords, issued a long-awaited conscription order to Pontus and the occupied territories, beginning to recruit a considerable number of conscripts to reduce losses during the siege.
In early December 1437, the Bosporus Army, having forcibly conscripted three thousand militiamen, primarily composed of heathens and ethnic minorities, totaling nine thousand troops, marched en masse towards Mtskheta.
The city was situated at the confluence of the Kura River's main branch and its left tributary, the Alagvi River, with its outer walls built on the Greater Caucasus Mountains of the Caucasus range, and its inner city located within the valley lowlands, making it easy to defend and difficult to attack.
Facing the mountains, he had conquered them before, from the Tauris Mountains of the Tauris Peninsula to the Pontic Mountains of Asia Minor, he had experienced it all firsthand.
However, on the advice of Ivan II and Dimitrios, along with other noble lords, he did not directly send phalanxes and artillery to bombard the city.
Instead, he first had the noble army, combined with a peasant militia unit, drive a group of conscripted militiamen to feign an assault on the city.
The result was tragic; just as most of them had ascended the scaling ladders, the Georgian defenders suddenly exerted force, pushing all the first wave of enemies they faced down, causing heavy casualties to this vanguard, with even some of the peasant and noble soldiers, who were supposed to be supervising, falling to their deaths on the ground due to their eagerness for glory.
After this, Manuel, refusing to believe in bad luck, ordered his troops to organize several strong assaults, but whether it was digging tunnels, taking waterways, or firing cannons, the Georgian army held them off.
Even during close-range cannon fire, the artillery occasionally misfired due to the cold winter, and was instead countered by the Georgian defenders in the city, resulting in the destruction of several cannons.
After more than a week of besieging Mtskheta, Caesar Manuel became somewhat anxious due to the lack of any real progress.
Fortunately, because logistics were not an issue and the attacking side was still united, the army's morale was essentially the same as before the siege.
In this situation, Caesar finally shelved the plan for a swift assault on the city and dutifully proceeded with a siege.
At the same time, he also began to rack his brains over the map, trying to find a special breakthrough point.
One afternoon during the daily siege of Mtskheta, as he was poring over the map, pointing with his pen, he suddenly discovered a potential breakthrough:
"I reckon the upper reaches of the Alagvi River are unguarded."
Just as he murmured to himself, the upper reaches of the Alagvi River, a left tributary of the Kura River, were at this time controlled by the Principality of Alagvi, which was temporarily loyal to the Bagration Dynasty.
Its Duke was Nugzar of the Shaburidze family.
They had always had marriage ties with the Bagration Royal Family and had consistently shown support for Tbilisi since the war began.
It was only recently, with the Bosporus grand army approaching Mtskheta, that Alagvi had quieted down somewhat, adopting a docile neutral stance to the outside world.
Manuel naturally scoffed at this so-called fence-sitting neutrality, but since taking Tbilisi was far more important than chastising these neutral lords, he had let it be.
But now it was different; facing this potential breakthrough, Manuel, as if suddenly enlightened, ordered his subordinates to immediately summon Ivan II and other lords, along with his generals, to discuss the feasibility of attacking from the upper reaches of the tributary.
The result greatly pleased him; according to Dimitrios, the Prince of Imereti, the northern side of Mtskheta facing the Principality of Alagvi indeed had relatively weaker defenses due to the Principality's constant protection.
Launching an offensive along the Alagvi River and Kura River was entirely feasible.
After all, centuries ago, the last time Mtskheta fell, it was taken by an attack from the west.
After confirming its feasibility, Manuel immediately set about formulating a secret plan and secretly sent people to Duke Nugzar of Alagvi, showing goodwill with an unconcerned attitude.
While lulling the other party, he also discreetly investigated whether he had any intention of defecting to him.
The results of the contact showed that although Nugzar accepted his goodwill, he was more in a wait-and-see attitude, and the Duke's personal feelings seemed to lean more towards his in-laws.
Given this, there was no need for Bosporus to hold back.
In mid-December, after preparations were complete, while personally overseeing the front line to maintain the illusion of an all-out siege of Mtskheta, five thousand lightly armored Bosporus and noble army elites, after bypassing the Greater Caucasus Mountains, like a sharp blade, under the cover of night, fiercely stabbed the Principality of Alagvi from behind the mountains in the northeast direction.
Due to the Principality's weak forces, Tbilisi's inability to provide support, and the rapid movement of this elite force, after about two or three days, Duke Nugzar was captured by the Bosporus Army in a daze inside the Ducal Palace in Dushet, the Principality's capital, and the Principality of Alagvi fell.
With the entire territory of the Principality of Alagvi falling under Bosporus's control, Mtskheta found itself under attack from two sides, which put the Tbilisi central government in a difficult situation.
Their enemy, on the other hand, after tentatively harassing the city's defenses with two teams of light boats via waterways, confirmed that the other party was indeed unable to withstand a pincer attack from two sides, and Manuel immediately smiled with joy in the grand camp.
"Good, it's time to open the door to Tbilisi."