There, shoulder to shoulder with their enemies, Radu and Nazira looked out on their countrymen. Tents had sprung up out of the mist like a growth of perfectly spaced mushrooms. Movement stirred the white tendrils of fog, offering glimpses of men who were then swallowed again.

“We are beset by an army of ghosts,” Cyprian whispered.

“Do not let anyone hear you say that,” Giustiniani said, his tone sharp. “We have more than enough superstition to contend with.”

“When did they arrive?” Radu asked. He leaned forward and squinted, even though he knew it would not magically help him pierce the moisture-laden air. Knew he would not see what—who—he wanted to. But he tried nonetheless.

“It must have been in the night,” Giustiniani said. “The damn fog has been so thick we did not even see them. I got reports of strange noises, and then it finally cleared some.”

“What should we do?” Cyprian asked.

“Wait until we can see something. And then we will start collecting information.”

Giustiniani had been right—visibility was poor, but sounds hung in the dead air. At times the noises were muted, as though coming from a very great distance. And sometimes they broke through with such startling clarity that everyone spooked, looking around in fear that the Ottomans were already behind the wall.

“Shovels,” Nazira said, pointing toward the camp. “You hear that rhythmic scraping?”

Giustiniani nodded. “They will be digging their own moat, a protective line for themselves. Building up a bulwark to hide their lines behind. And generating material to try to fill in our fosse.”

Another sound cut through the air. Radu had half turned before he realized what he was doing. The call to prayer, and Radu could not answer. He had prayed too early. Nazira’s hand found his, gripping tightly. They stood, frozen, until it was over.

“Filthy infidels,” a man to Giustiniani’s right said, spitting over the wall. “The devil’s own horde.” Then the man straightened, brightening. “You hear that? Christians! I know that liturgy. We are answering them! I—” He stopped, his eyebrows drawing low. “Where is it coming from?”

“Outside of the wall,” Cyprian said, his voice as heavy and blank as the fog.

“Mercenaries?” Giustiniani asked.

Radu realized the Italian had been addressing him. “Probably men pressed into service from vassal states: Serbs, Bulgars, maybe even some Wallachians. And then anyone who came willingly when they heard of the attack.”

“Why would Christians come against us?” The soldier’s face was twisted with despair. He turned to Radu as though he held all the answers.

It was Giustiniani who spoke, though. “For the same reason they sent us no aid. Money.” This time he spat over the wall. “How will he organize?”

Radu leaned against the wall, turning his back on the Ottoman camps and staring toward the blank white bank of fog. Only one thing rose up high enough to pierce it—the spire of the Hagia Sophia. The cathedral the city left dark. “Irregulars and Christians at the fronts on most areas of the wall. Places he thinks are less important. He does not trust anyone who is here solely for money. Janissaries and spahi forces at the weakest points—the Lycus River, and the Blachernae Palace wall section.”

“So he will be weak where the other forces are weak. If we sallied out, broke through—”

Radu shook his head. “He will have enough men to spare to make certain the irregulars maintain as much order and discipline as possible. There will be no breaking point in his lines. He will concentrate his attacks on your weaknesses, but he will have no weaknesses vulnerable to direct attack.”

Giustiniani sighed. “So we wait.”

“So we wait,” Radu echoed.

The next day dawned bright and clear. From the looks on the soldiers’ faces, they wished it had not.

Radu was once again at Giustiniani’s side, along with Cyprian. Nazira had stayed home. Her parting embrace had been too tight, her whispered caution tucked around him. Radu had to be more careful than ever.

Giustiniani handed him a spyglass. He pointed toward the back of the camp, in a corner where smoke was billowing upward. “What are they doing there?”

It took a moment for Radu to focus, and another few moments for him to train the glass on what he was trying to find. Familiarity warmed him, and he hid his affection behind a grim look. “Forges,” he said, handing back the glass.

“What do they need forges that big for?” Cyprian asked.

“Cannons.”

“They are going to make cannons on the battlefield?” Cyprian laughed. “Are they also planning on a brick kiln? Building a wall of their own while they are at it?”

“I think it is to repair cannons, mostly.”

“They would need a tremendous amount of supplies.” Giustiniani frowned. “The logistical aspects would be a nightmare. Do you think they could actually do it?”

“I do. Mehmed—” Radu cringed, and started over. “The sultan is organized and methodical. He has resources he can pull from two continents. If he needs it, it is already here or on its way. I have been in an Ottoman siege before, under the sultan Murad. This will be even bigger, cleaner, more efficient. Mehmed watched and learned. He will have enough supplies to last as long as he needs. The men will be limited to one meal a day to preserve food. He will keep things meticulously ordered and clean to prevent sickness.”

Giustiniani pointed toward the rows of tents. “By my estimations, there are almost two hundred thousand men out there.”

Cyprian let out a breath, as though he had been hit in the stomach. “That many?”

Radu nodded. “But roughly two men in support for every one man fighting.”

“That still leaves sixty thousand? Seventy thousand?” Cyprian covered his mouth with his hand. Radu was shocked to see tears pooling in his gray eyes. “So many. What could Christianity accomplish with a mere fraction of the unity Islam has? How can our God ever withstand the ferocity of this faith?”

“Do not blaspheme, young man.” Giustiniani’s tone was sharp, but it softened when he spoke again. “And do not despair. The odds are not so against us as they look.” He patted the stone in front of them with one thick, callused hand. “With a handful of men and these walls, I could hold back the very forces of hell itself.”