The Siege Of Canterlot

General Summerstrike was proud of the Corona Line. He was proud of the labourers who had toiled for so long to construct it, and he was proud of the ponies who manned its battlements and protected the forts. As its commanding officer, that was to be expected. But he was also proud of what it represented. The Corona Line was named after Celestia's crown, that symbol of high and holy office that the Princess wore. Each fort represented one of the points of the diadem, three in total, guarding the southern approaches into the Foal Valley, where the capital city lay. Like the forts of the Hornburg Line, they were modern, designed to be resistant to artillery fire, strong walls of stone reinforced with earth and low buildings to minimise the silhouette for enemy gunners.

They were also designed for a specific purpose, and that purpose was to dominate their immediate surroundings. A fort could control a key terrain feature, such as a mountain pass, the entrance to a valley, or a river ford. The Corona Line had been constructed to defend both the entrance to the Foal Valley and also the approaches to the Henbane River, which lay to their north. There were a couple of older forts there, guarding the most accessible river crossings, but it had been decided that the best approach was to try and limit enemy access into the valley in the first place. The great military architect and planner, Ferdinand Firetail, had drawn up the plans for the fortresses and overseen their construction, an undertaking which took several years and several million bits apiece to complete. There had been some suggestion of placing the forts at the Henbane itself to defend the river, but that would have meant spending even more of the treasury's coffers, already depleted after the construction of the Hornburg line at a similarly exorbitant cost, in tearing down the old fortresses that were already located there. Firetail, Celestia and Hawkeye had agreed between them that an extra layer of protection for the river and valley would be the ideal way to proceed, and so it had been done.

Firetail, whose colours matched his name, with a wild mixture of red, orange, and yellow to be found all over his body and mane, was one of Equestria's great current military minds. Formerly a Colonel in the Royal Guard, and a footsoldier and junior officer in the infantry for years before that, he had studied architecture and military history at the highly prestigious Canterlot University after one of his uncles, a minor noble, died and elevated Firetail, so to speak, to the fringes of the aristocracy. Despite his humble beginnings as an apprentice blacksmith and thence a mud-wallower in the infantry, Firetail took to his studies with a voracious appetite and graduated top of his class. Only those of noble birth or marriage, or military officers, who unlike in some nations could be of any stock, could study at the royal university, and to graduate in any subject was noteworthy.

To come top of a highly competitive class in his joint subject was something to be applauded, and applauded it was. Firetail was quickly informed that he was due to marry a mare he had never met, as befitted his new noble status as a very minor baronet. So it was that his union with his new wife, Rosehip, the daughter of the Marquess of Trottingham, came to pass, as well as his appointment as commander of the Royal Guard garrison at Stalliongrad, a post he held for several years, leading successful counter-insurgency operations against gangs of Moon Cultists and Griffon border pirates. All the while he was working, sketching, drawing, sculpting his ideas for forts, fortified cities, border defences. His one aim in life was to protect Equestria- and, after two years of marriage, to protect his newly born daughter as well.

Promotions and appointments continued until he was called to oversee the construction of a new fort on the northern border with Yakyakistan, to replace a decrepit pile of masonry which had partially succumbed to a landslip and now resembled not so much a fortress as a kind of crumpled chamber pot with the handle missing. Under his direction, a brand new, modern, well-armed fort had been erected to guard the northern reaches. It had withstood a massive assault by a rogue Yak warband who had strayed from the fold and attacked against the orders of their Crown Prince. Only a dozen ponies had died and the walls had held against heavy artillery and old-fashioned catapults alike, earning Firetail the praise of his superiors, including the Princess, who had appointed him to design two more forts elsewhere in the land, and then ultimately the improvement and modernisation of the walls of Canterlot itself, culminating in the construction of the new defensive lines, the Hornburg and the Corona.

However, as General Summerstrike observed ruefully from the battlements, the skill and money poured into the construction of the Corona Line did not mean it would prove particularly useful in the war. The Shadow Army evidently had a single main aim; to drive north as fast as possible, and capture Canterlot. That was the logical end goal for them, pushing up the valley all the way, punching through anything in their path. That was exactly what they were doing; they had taken Trottingham easily enough, but when confronted by the Corona Line and its trio of forts, they had evidently decided to bypass them entirely.

That was the main issue with a fixed defensive line; unless you also had a strong army in the field, it was entirely possible for the enemy to slip through the gaps between forts with little to hinder them. The garrisons of each fort were strong enough to mount local counterattacks, but not to stop a determined push against a numerically superior enemy, even if they could coordinate effectively between garrisons, which was difficult given that each fort was miles from the next, thanks to the width of the valley. To avoid attracting cannonballs, the forts also lacked high towers as would be found in most fortified cities, meaning they were reliant on Pegasus observers to see what was happening to their fellow strongholds. As it was, Summerstrike and the rest of the garrison at Fort Corona simply had to stand and watch in dismay as the vast majority of the enemy simply marched past, between their fort and their eastern neighbour, sweeping aside the meagre defences strung out between the strongpoints, leaving behind small but sufficient numbers of troops to invest and besiege the forts, keeping their garrisons bottled up and unable to counter the bulk of the Shadow Army and their Changeling auxiliaries. Not that they would have been able to anyway; if they had taken to the field, the garrison troops would have been slaughtered, outnumbered horribly by the huge enemy force.

General Summerstrike sent messengers north, as soon as the enemy began to march through the gaps and as soon as he could get a rough estimate on their strength. He confirmed that the previous estimate, from Colonel Graves at Trottingham, was broadly accurate, and estimated the enemy's numbers at between one hundred and one hundred and twenty thousand. That, he clarified, was the strength of the force that was proceeding northward. They had left behind at least twenty thousand more troops to besiege the forts. He again urged in the strongest possible terms that every available unit be sent to hold the Henbane River against the horde. His messengers reached Canterlot, and his pleas were heard by Hawkeye and Starswirl. They were acted upon. But that was not enough.

The Henbane River was the lifeblood of the Southern Province, the mighty artery that flowed down from the high peaks of the Southern Foals and out across the valley before emptying, eventually, into the Great Western Sea several hundred miles away to the west, where it formed the northern border of the Shadowlands with Griffon territory. By the time it arrived at the ocean it was a vast delta, some eight miles wide and surrounded by estuarine marshes and low-lying swamps. North of the Corona Line, however, it was a fast-flowing, half-mile wide, but fairly shallow river. Shallow, however, was a relative term, for it was completely unfordable for the most part. For the majority of its length as it passed through the valley, the Henbane could only be crossed by bridges, of which there were three; two of stone and one of wood. At Summerstrike's order, the garrisons of the small forts that controlled the bridges had destroyed them by detonating stores of gunpowder, denying their use to the enemy and blocking any easy passage across the river.

However, at two key points where the river cut across the valley, rocky outcroppings of hard schist protruded from the earth and formed a firm surface below the water, worn smooth by the hydraulic action over countless years. Here, and only here, an army could ford the river in relative safety. Infantry could wade across, horses could pass through, and supply wagons and cannons could be towed to the other side without being inundated or washed away. These two fords were the key to accessing the valley beyond, which was why castles and other defensive fortifications had been built there long ago.

The two castles and their earthworks and blockhouses controlled the fords, constructed many years ago. The strategic importance of the two sites had long been known, and Equestria had sought to control them in order to restrict crossings of the river, which ran east to west, and to control access into the glacial valley that ran north to south., within which Canterlot lay. The two sites had been reinforced by contingents of the Provincial Armies of both the Southern and Central Provinces in anticipation of the enemy advance, with some companies marching day and night from the towns of Ponyville and Clopham Junction to reach their positions. The crossings were well defended, with cannons covering the fords and musketponies aplenty. None of it made a difference, for one simple reason.

The enemy did not use the fords.

Nor did they use the bridges, as their scouts quickly determined they had been destroyed. Instead, they found a clear stretch of the southern bank, well out of range of any defences, and began to construct their own bridge. The Changelings and Pegasi in their ranks simply flew over the river at the undefended spot to establish a bridgehead on the far side, quickly adopting a combat posture in case Equestrian forces arrived. Meanwhile, their engineers were busy floating empty boats out into the stream, over which they rapidly constructed a makeshift pontoon bridge, using their magic to rapidly assemble planks of wood, roping them together, securing them to the boats which had been carried with the army's supply train for just such a purpose. It did not take all that long, a few hours, but it was long enough that the Equestrian forces who had rushed to augment the defences at the fords were able to reposition once their scouts learned of the pontoon construction. Every available pony was rushed to the location to try and prevent the crossing.

They failed.

Exhausted by their rapid forced march and confronted immediately upon arrival by a mass of Changelings and Pegasi, the Equestrian infantry formed up as best they could. They had no artillery, but some of the Shadow Army's guns were able to deploy on the south bank and provide supporting fire. They had no cavalry, either, though the enemy riders were confined to the south bank until the bridge was completed. But most importantly, they were arriving piecemeal. Companies were arriving from different sites at different times, from the bridges and the fords and from the reserve. They had different distances to travel, and to form them up elsewhere and then advance as one body would just give the enemy time to complete the bridge and rush their best units across to fight. Whatever the defenders did, they were doomed to fail. Without a large force, they could not hope to control the entire river. They tried their best, fought bravely, and died, felled by the swords and muskets of the Changelings and the Pegasi of the Shadow Army. They inflicted casualties, but in return they were shattered, forced to retreat in disarray. The pontoon bridge was completed, and the invaders began to stream across. Infantry, cavalry, artillery. All headed north. Their objective was clear, and they were confident of reaching it. The river had been the last major obstacle, and they had overcome it with ease and minimal loss. The way ahead lay open.