Giustiniani cleared his throat, spitting. He had so much stone dust in his hair he looked as though he had aged thirty years. He considered Radu thoughtfully. “Are you an expert in cannons, then?”

“Not an expert. But none of these towers are equipped for cannons. They are not strong enough, and there is not enough room to support the guns. You will have to figure out another way to use them.”

“We thought if we could fire back at the sultan’s cannons, we could—”

“Too small a target. By the time you used enough shots to get the range right, they would move their guns. You have seen their camp. If you managed to destroy even one cannon, they have the means to repair and cast new cannons. I am certain Urbana will be with them. No one is better than she. And I am guessing they have dug in and are firing from behind a bulwark.”

Constantine nodded grimly. “That first shot at the Saint Romanus Gate—even I thought the world was ending. But it has not been repeated. Maybe the cannon broke?”

Radu tested his shoulder. He could move it, but the pain was excruciating. “The Basilica.” He almost smiled, thinking how delighted Urbana would be. “It has to cool between firing, so it’s limited to several shots a day. It was more to prove they could than for any practical use. It is the number of guns you should fear, not the size of one. Are the walls holding?”

Giustiniani shook some of the grit from his hair. “So far there are no holes big enough to threaten us. They fire wrong. They should fire in sets of three, one on each side and then one in the middle, to bring a whole section down. Instead, they fire at the same spot over and over again. They are doing damage, but not enough.”

Giustiniani leaned out, watching without flinching as a massive ball shattered against the wall some ways down from them. The sound was louder than any Radu had ever heard, like thunder smashing against thunder.

“We cannot absorb these blows. The fragments from the wall are as likely to kill our men as the cannon shot itself.” Giustiniani was silent for a while, deep in thought. “We cannot answer their cannons, nor can we trust the strength of the walls.” He smiled grimly. “It is time to become more flexible.”

Because of Radu’s shoulder injury, he helped Cyprian with organizing rather than going to fix the walls. All day they ran, directing men to dump mortar paste down the walls to strengthen them. They attached rope to bales of wool and lowered them to absorb impacts. The palace was raided of all tapestries, the elegant stitching and bright depictions of the past now draped over the walls in a desperate attempt to secure a future.

By nightfall, everyone in the city was wide-eyed and trembling from the ceaseless bombardment. But they were ready. As soon as it was dark, Giustiniani sent the supplies up. At each significant breach in the wall, they put down stakes with stretches of leather hide nailed tightly between them. Into the space between the hides and the remains of the wall they dumped stones, timber, bushes, brushwood, and bucket after bucket of dirt.

A few stakes to save a city.

“Will they burn?” Radu asked Cyprian as they oversaw a patch along the Blachernae Palace wall.

“The hides will not light easily. But we will need to station guards with crossbows to keep men away, regardless.” Cyprian paused to shout directions to men rolling large barrels packed with dirt toward them. “Along the top so we have something to hide behind!”

The men had only just finished placing the barrels when a stone ball came sailing out from the blackness. Radu did not have time to hold his breath as he watched it smash directly into the makeshift wall.

The loose materials held by the skins absorbed the cannonball’s impact, and the ball rolled harmlessly to the ground.

The men around them cheered. Many dropped to their knees in prayer. Cyprian whooped joyfully, throwing his arms around Radu in a hug. Radu cringed at the pain in his shoulder, and at the shout of joy that had escaped his own lips before he realized he was cheering for the wrong side.

The next five days brought no rest, no change. The cannons fired, the sound of stone shattering stone so constant Radu stopped noticing it. The acrid scent of smoke was everywhere. When he came home to sleep for a few hours, Nazira made him dump water over his hair outside to try to rinse some of it away.

But as soon as sleep claimed him, the noise from the wall would jar him awake. He stopped trying to go home, instead slumping in the shadow of the inner wall for a few minutes of rest. The hours blurred, only the sun or the moon marking the passage of time. Even those were so obscured by smoke that they were hardly visible.

In addition to the ceaseless bombardment, Ottoman troops threw themselves against the walls at random. They used hooks to pull down the barrels of earth protecting the defenders. The Ottomans were packed so tightly that a single shot of a small cannon could kill several, yet still they came.

That was the part Radu wished he could block out, the acts that made him certain he could never wash the scent of the wall from his soul. Because he had to be on this side, and he had to play his part. And so, when the Ottoman soldiers—his brothers—ran up to try to retrieve the bodies of their compatriots, he sat on top of the wall with the enemy and picked them off one by one.

The first time he hit a man, he turned and vomited. But soon even his body was numb to the horror of what he was doing. That felt worse. With each shot he prayed he missed, and with each hit he prayed the walls would fall soon and spare them all.

On the sixth day of the bombardment, an explosion cracked through the air, echoing off the walls. It was notable only because it had not come from the walls—it had come from the Ottoman camp.

Radu ran to the top of the wall, leaning over. Black smoke billowed from the bank of earth that hid the Basilica. The location of the cannon had been identified on the first day, but Giustiniani had not been able to destroy it. They had not needed to, apparently.

Even from this distance the devastation was obvious. The gun must have finally succumbed to the heat and pressure of so many firings and exploded. Radu wiped furiously at his face, his hands leaving more grit than they cleared away. He had no doubt that Urbana had accompanied Mehmed to take care of her precious artillery. Had her greatest triumph been her end?

An exhausted and ragged cheer rose around him, but this time he could not even pretend to join in. The Basilica was gone. The wall still held. And his friend was more than likely dead.