Conquest

Once more, as he had in 1066, William would confront a military challenge across an expanse of water.

Throughout the early summer of 1071, the Norman army gathered around Ely and William’s newly commissioned ships sailed into fenland waters.

The fleet consisted of standard longships carrying butescarls, smaller, flat-bottomed boats to navigate shallow waterways, and vessels adapted to carry catapults and ballisti. There was also a flotilla stationed in the Wash to act as supply ships and to prevent any naval ambush by Danish or Scottish allies of the Brotherhood.

On land, William ordered permanent camps to be prepared on the solid ground around the Isle of Ely and assembled a formidable show of strength. There were 4,000 infantry, 40 squadrons of cavalry, 500 archers and crossbowmen, and an array of blacksmiths, sappers and shipwrights. He had thought carefully about the assault; his planning, as always, was scrupulous. He intended to use catapults on any surrounding hillocks and islands that were within range of Ely and build tall towers for ballisti that could hurl stones, fire and boiling oil at the defenders. Finally, and most significantly, he intended to use pontoons to construct a new causeway for a final assault on the island.

When all the King’s forces were in position, the Brotherhood was heavily outnumbered. Just 3,000 defenders faced an amphibious Norman assault force of almost 8,000. Crucially, William was able to bring in more men, equipment and materiel to an all but limitless extent.

The first assault would come from ground to the south-east of the island. While archers and crossbowmen loosed hails of arrows, and catapults launched their projectiles on to the Isle, Norman sappers would build a new causeway to the island. It would be a floating pontoon to span a stretch of water almost 800 yards across. The causeway would have to fall short of the island by about 200 yards because of the threat from the arrows of the defenders, but William estimated that his horses could cope with the shallow water at that point and reach the island. When it was completed, William planned to mount a cavalry attack with infantry in support.

Hereward’s defence on the landfall side was a high peat bank and ditch. However, to prevent him massing too many defenders behind the bank, William planned simultaneous amphibious attacks all around the island, thinly stretching Hereward’s forces around Ely’s twenty-mile perimeter. Communications would be vital for the defenders, and Martin Lightfoot’s messengers would have one of the most difficult tasks.

When, several weeks later, the pontoon was ready, William’s first cavalry attack, early on a clear June morning, was heralded by a single arrow shot high into the sky. Dawn had brought an amber glow to the water and the distant clouds were framed by golden sunbursts. There was silence, the meres and waterways of the Fens still, but the calm was soon interrupted by the rumble of heavy cavalry. As the riders began to cross the causeway, three abreast in tight formation, their horses’ hooves clattering on the timber of the new bridge sent a chilling echo around the Isle.

The attack was a hopeless failure.

William had to put a large body of cavalry on to the causeway for the attack to have any momentum, but the structure appeared unable to support such a volume of men and horses, especially in the middle where it crossed the much deeper course of the River Cam. The pontoon began to give way after about 250 yards, and the charge lost its discipline. The lead horses panicked and, within minutes, hundreds of men and their steeds were floundering in the murky waters and deep mud.

Few got out alive.

William ordered his senior engineer to be executed on the spot and twenty of his sappers were flogged in front of the entire army.

Although the design of the pontoon was flawed, what William did not know was that its imperfections were significantly exacerbated by Hereward’s cunning. Night after night, Alphonso and Hereward and their squads of saboteurs had slipped into the cold waters of the Great Fen to partially sever the structure’s ropes and timbers beneath the waterline. Thanks to their handy work, the pontoon was doomed.

William rarely made mistakes, so to have made two in one day was unprecedented. Not only had he built an inadequate causeway, he had also failed to realize the significance of the day chosen for the attack. If he had owned an astrolabe, he would have known that it was the twenty-third day of June.