The three generals watched with grim concentration as the army of Hungary formed up on their side of the river. It took an age and Tsubodai noted every detail, pleased that they showed no more discipline than any of the other armies he had encountered. The reports from Baidur and Ilugei were good. There would be no second army coming from the north. In the south, Guyuk and Mongke had razed a strip of land as wide as Hungary itself, throwing back anyone who looked as if they could be a threat. His flanks were secure, as he had planned and hoped they would be. He was ready to drive through the central plains, against its king. Tsubodai rubbed his eyes for a moment. In the future, his people would ride the grasslands of Hungary and never know he had once stood there, with their future in the balance. He hoped they would throw a drop of airag into the air for him when they drank. It was all a man could ask for, to be remembered occasionally, with all the other spirits who had bled into the land.

King Bela could be seen riding along the lines, exhorting his men. Tsubodai heard hundreds of trumpets sound from the massed ranks, followed by streaming banners raised above their heads on lance-poles. It was an impressive sight, even to men who had seen the armies of the Chin emperor.

Batu watched them in frustration. Presumably Tsubodai would share his plans with him at some point, perhaps when he was expected to risk his life to break that vast host of men and horses. His pride prevented him from asking, but Tsubodai had revealed nothing during day after day of cautious manoeuvring and scout reports. The tumans and conscripts waited patiently with Chulgetei, just two miles back from the river.

Already, the Magyar scouts had spotted the generals leaning on their saddle horns and observing. Batu could see arms pointing at their position and men beginning to ride out towards them.

'Very well, I've seen enough,' Tsubodai said. He turned to Batu. 'The tumans will fall back. Slow retreat. Keep…two miles between us. Our footmen will have to run alongside the horses. Pass the word that they can hang on stirrups, or ride the spare mounts if they begin to fall behind and think they can stay in the saddle. The king has foot soldiers. They will not be able to force a battle.'

'Fall back?' Batu said. He kept his face calm. 'Are you going to tell me what you have planned, Orlok Bahadur?'

'Of course!' Tsubodai said with a grin. 'But not today. Today, we retreat from a superior force. It will be good for the men to learn a little humility.' Sorhatani stood on the walls of Karakorum, looking along their length as the sun rose. For as far as she could see, teams of Chin labourers and warriors were building them higher, adding courses of limestone slabs and lime cement, before slathering more lime over it all in layer after hardening layer. There was no shortage of willing labour and they started early and finished only when it was too dark to see. Everyone with a stake in the city knew that they must expect Chagatai Khan to come. He would not be allowed to enter and there was no doubt then what would follow. His tumans would begin an assault on the walls of their own nation's capital.

Sorhatani sighed to herself in the morning breeze. Walls would not stop him. Ever since Genghis had faced his first city, the tumans had been perfecting catapults and now they had the gritty black powder capable of extraordinary destruction. She did not know if Chagatai's artisans had followed the same paths, but it was likely he knew every detail of the latest cannons and barrel-throwers. To her left, a platform for a field gun was being constructed, a squat tower capable of taking the weight and force of such a powerful weapon as it recoiled.

When he came, Chagatai would not have it all his own way, she had made sure of that. The city would belch fire at him and perhaps a tongue of righteous flame would end the threat before he broke the walls and entered the city.

Almost from habit, Sorhatani counted the days since the khan's death. Twelve. She had closed the yam station in the city as soon as her own message had gone out to Guyuk, but the system was flawed. Another chain of way stations stretched west from Karakorum to Chagatai's khanate, fifteen hundred miles or more. A rider from the city had to reach only one link in the chain and the resources of the precious yam could be used to send Chagatai word of the khan's death. She thought over the distances again in her head. At the best speed, he would not hear for another six days. She had gone over the figures with Yao Shu as they began to fortify the city. Even if Chagatai set out immediately, if he ran to his horse and had his tumans standing by, he could not bring his tumans back for another month after that, more likely two. He would have to follow the yam route around the edge of the Taklamakan desert.

At the best guess, Chagatai khan would arrive in midsummer. Sorhatani shaded her eyes to look at the progress of the workers on the walls, their faces and hands grey with wet lime. By summer, Karakorum would bristle with cannon, on walls wide enough to hold them.

Sorhatani reached down and crumbled a piece of chalky stone in her hands, rubbing it to dust and then slapping her palms together. There was a great deal still to do before then. She and Torogene were holding the empire together with little more than spit and confidence. Until Guyuk brought the tumans home and assumed his father's titles, until the nation gathered to swear an oath to him as khan, Karakorum was vulnerable. They would have to hold the walls for two months, even three. Sorhatani dreaded the thought of seeing a red or black tent raised before Karakorum.

In a strange way, it was Ogedai's triumph that the city had assumed such importance. Genghis might have called the nation to him, somewhere out of sight of the white walls. Sorhatani froze for a moment as she considered it. No, Chagatai did not have his father's imagination, and truly Karakorum had become the symbol of the people's ascendancy. Whoever would be khan had to control the city. She nodded to herself, ordering her thoughts. Chagatai would come. He had to.

She stepped lightly down steps set into the inside of the wall, noting the wide crest that would allow archers to gather and shoot down into an attacking force. At intervals, new wooden roofs sheltered spaces on the wall that would house quivers, water for the men, even fire-pots of iron and clay, filled with black powder. The city Guards were stockpiling food as fast as they could, riding out for hundreds of miles in all directions to commandeer the produce of farms. The markets and livestock pens had been stripped of their animals, the owners left with just Temuge's tokens to be redeemed at a later date. The mood in the city was already one of fear and none of them had dared to protest. Sorhatani knew there were refugees on the roads east, slow trails of families hoping to escape the destruction they saw coming. In her darker moments, she agreed with their conclusions. Yenking had held out against the great khan for a year, but its walls had been massive, the product of generations. Karakorum had never been designed to withstand an attack. That had not been Ogedai's vision of a white city in the wilderness, with the river running by.

She saw Torogene standing with Yao Shu and Alkhun, all of them looking expectantly at her. Nothing went on in the city without passing through their hands. Her heart sank at the thought of another hundred problems and difficulties, yet there was a part that revelled in her new authority. This was how it felt! This was what her husband had known, to have others look to you, and only to you. She chuckled at the sudden image of Genghis hearing that his fledgling nation was ruled by two women. She remembered his words, that in the future his people would wear fine clothes and eat spiced meat and forget what they owed to him. She kept her expression serious as she reached Yao Shu and Torogene. She had not yet forgotten that fierce old devil with the yellow eyes, but there were other concerns and Karakorum was in peril. She did not think her right to the ancestral lands would last long once Chagatai became the khan of khans. Her sons would be killed as the new ruler made a clean sweep and put his own people in charge of the nation's armies.