Lightning said, ‘That is an understatement. Think what it’ll be like for the battalions in the rear after the first ten thousand have walked over it in front of them. We will need a whole division to lay duckboards as they go. We will progress slowly across the drained lakebed, keeping in line, chopping down the Insects’ buildings. Without…’ He savoured the words: ‘Without any expectation of casualties at all.’

‘I’ve never been in an Insect cell before,’ Eleonora said thoughtfully. ‘But they’re too close together to take horses through.’

Lightning said, ‘When we reach the new Wall, we will secure the area, continue to dismantle the cells and bring up some trebuchets. The Queen’s lancers will patrol and act as rearguard.’

The wind was ruffling Lightning’s dark blond feathers and making them stand upright. Irritated, he shook his wings out and folded them tightly. I can’t believe he gave Eleonora his coat. Doesn’t he know her reputation? I looked at him carefully, thinking that even he must be aware of the ribald rumours. Eleonora was the only child of Lord Governor Osprey Tanager, who was killed by Insects twenty years ago, the last of that family. When she was not at the front she held court in Rachiswater Palace, but as soon as she had rebuilt her family’s manor house she intended to restore the capital of Awia to Tanager, as it was in 1812 before the Rachiswaters took the throne.

The lake reflected the banded mackerel sky, with thin clouds the grey-purple colour of an artist’s paintbrush water. Trochanter, the morning star, was growing fainter. Below, the surface of the river winding east towards Lowespass Fortress had an oily, rainbow scum of old poison washing out from the Wall.

We crossed a bridge over the dry overspill chute and descended to the shore. The two soldiers guarding the access to the walkway uncrossed their spears promptly and we passed between them.

A beacon basket full of twigs and hay stood next to a large bell on a pole and my semaphore device set at neutral. Their metal stands prevented Insects eating them. Eleonora’s bodyguard of four Tanager Select lancers sat obediently at attention on their warhorses. She appraised them out of habit: their embossed armour, the woollen cloaks hanging to their stirrups, their helmets with blue and white striped horsehair crests and fluttering muslin streamers. They love ornamentation, do Awians.

Eleonora’s horse waited between them. The silver inlaid armour on his head was richer than anything I owned. The chafron plate beaked over his nose came to a point; the crinet covering his neck was steel openwork, scallop-edged like batwings. Lightning’s horse was drab in comparison. Eleonora greeted them enthusiastically, ‘Hello, Perlino! Hello Balzan!’

Perlino looked skittish at my scent. He put his ears back and flared his nostrils imperiously. ‘I don’t like you, either,’ I told him.

Eleonora patted his neck and he nuzzled her hand.

I said, ‘It isn’t my fault most horses are afraid that Rhydanne want to chase them down and eat them.’

‘Maybe I should take Perlino to Darkling and give him a sniff of pure Rhydanne for comparison. Then he’d appreciate you.’ She fitted her toe into a stirrup, swung herself onto the horse. She sat straight, holding the reins loosely. Perlino high-stepped with his strong front legs, in rein-back, then Eleonora made him pirouette.

She leaned from the saddle and prodded my chest, ‘Race you!’ She tapped Perlino’s flank and was away down the track. Her bodyguard looked at each other and followed suit, standing on their stirrups, their lances tilting backwards in their saddle rests.

Lightning hesitated, surprised, then stepped up astride Balzan, drew his reins left, turned and sped after her. They picked up the pace from a gallop to a charge; I watched them disdainfully until they were just dots above clouds of spray. Then I sighed, shook my wings open and ran to take off.

Frost had given me days to prepare a speech but as usual I hadn’t bothered; I’m used to speaking ad lib. I stood outside the hall listening to the low hubbub and expectant atmosphere. It reminded me of court.

Everybody looked up as I entered and silence descended over the benches filled with journalists and their assistants, saddle-sore in crumpled clothes.

Frost was sitting on a bench by the front wall, facing them. She fiddled with her river pearl wedding ring, her only jewellery, but she looked meditative rather than nervous; she was probably passing time by working out equations in her head.

A number of architects and engineers sat on the furthest benches. Many were women, watching their role model with expressions of adulation, fountain pens poised to scribble on sheaves of paper on their knees. I scanned the room for familiar faces, thinking: I’ll watch out for the Morenzians, they tend to be the least respectful-but I spotted Kestrel Altergate, the exception to the rule.

Frost had taped a schematic drawing of the dam to the chimney breast. I stood in front of it and addressed the audience. ‘Good morning, everybody. Welcome to Slake Cross, representatives of the governors and of the press. I know you’ve made many days’ journey and I apologise that the lodgings we have to offer are of necessity fairly basic.

‘Tonight is the centenary of the battle of Slake Cross. On this very night, one hundred years ago, thousands of Insects emerged from the cave system under the river, into the middle of a vanguard camp of five battalions. Only thirty mortals survived, all archers who showed incredible courage.

‘I was there, and can never forget, but even for those who were not, the date is charged with meaning. We were forced to retreat in this part of the valley. Here and only here, for the first time since the foundations of Lowespass Fortress were laid in the year ten-oh-nine, the Insects extended their Wall on the south side of Oriole River. It is our vulnerable spot. For exactly a century the Castle has been striving to push the Wall back and reclaim our land. A hundred years and-by god-it seems like a long time!’

I waited until the journalists’ polite laughter had subsided and then I opened my wing towards Frost. ‘The Circle’s Architect has taken five years to design and build the dam, the largest construction ever. It is truly the wonder of the modern world.

‘Insects may be instinctive architects but they had to run when the river began to expand. I watched from the air, I saw them drowning, curling and twisting. Now, next week we will drain the lake and you are all invited to witness the prodigious sight. It’ll be the biggest waterfall you can possibly imagine.’

My enthusiasm made them sit up. I was very excited at the prospect of seeing millions of tonnes of water spurting into the river. ‘As the lake level drops, the Insect buildings will gradually emerge, slick and slimy.

‘All the immortals will lead the fyrd to secure two hundred square kilometres of land and the north bank of the river. We have battalions already drawn up from coastal Awia-that is to say, the manors of Tanager, Peregrine and Wrought-and Lakeland Awia, the manors of Micawater and Rachiswater. I have also requested battalions from Hacilith and Eske, so you see the Empire’s other capitals are participating with good will.’

Kestrel Altergate, on the first row, tried to interrupt me, ‘Comet-’

I raised a hand, ‘Please wait and I’ll take questions at the end. I’d like to hand you over to Frost, who will give some more details of her magnificent achievement.’

I waved her up extravagantly and went to sit down. As we passed each other I clapped her shoulder and leant to mutter in her ear, ‘Don’t bog them down with technicalities.’

Frost stood behind her table, using it as a barrier between her and the audience, speaking over the top of her papers. She smiled, and a lifetime of looking uptight disappeared from her face. She held her hands apart and expanded the distance between them as she expounded her thoughts. ‘I have built the dam where the Insect Wall crossed the river. Its wall is two kilometres long and thirty metres high. It holds back a lake twenty kilometres in length. The dam is an embankment, an earth mound with a core of rubble, faced with protective stone. It is an economical construction-the fyrd are used to building earthworks for our defences and this is no different. It is constructed around piers set into the former river bed.’