She is enlisted with several hundred other children to help shore up deteriorated sections of the walls. They haul paving stones, flagstones, even grave stones, and hand them up to bricklayers who mortar them into place. As though the whole city is being disassembled and rebuilt as an endless wall.

All day she lifts stones, carries buckets; among the masons working on scaffolding above her are a baker and two fishermen she recognizes. No one speaks the sultan’s name aloud, as though saying it might cause his army to materialize inside the city. As the day wears on, a cold wind rises, the sun subsumed under swirls of cloud, and the spring afternoon feels like a winter night. Along the ramparts above them, barefoot monks carry a reliquary behind a crossbearer, chanting a low and somber song. Which, she wonders, will be more effective at keeping out invaders: mortar or prayer?

That night, the second of April, as the children drift back toward their homes, cold and hungry, Anna picks her way through the orchards near the Fifth Military Gate to the old archer’s turret.

The postern is still there, full of debris. Six turns to the top. She yanks away a few creepers of ivy; the fresco of the silver and bronze city still floats among the clouds, gradually flaking away. On her tiptoes, Anna reaches to touch the donkey, eternally stuck on the wrong side of the sea, then climbs out the west-facing archer’s loop.

What she sees, beyond the outer wall, beyond the fosse, turns her cold. Groves and orchards like the ones she and Maria passed through a month before on their way to Saint Mary of the Spring have been hacked down and in their place stretches a wasteland bordered by wooden posts, sharpened at their ends and rammed into the earth like the teeth of enormous combs. Beyond the spike walls and palisades, which extend as far as she can see in both directions, lies a second city haloed around the first.

Thousands of Saracen tents flap out in the wind. Fires, camels, horses, carts, a great distant whirling blur of dust and men, all in quantities so large she does not possess the numerals to count them. How was it that old Licinius described the armies of the Greeks as they assembled outside the walls of Troy?

But ne’er till now such numbers charged a field:

Thick as autumnal leaves or driving sand,

The moving squadrons blacken all the strand.

The wind shifts and a thousand cookfires flare brighter, and a thousand banners flap on a thousand standards, and Anna’s mouth goes dry. Even if a person were able to slip out a gate and try to flee, how would she ever pick her way through all that?