The force assembled in the estuary of the river Dives, facing England, lodging in tent cities. There would be two thousand cavalry, eight hundred archers, three thousand infantry and a thousand sailors, supported by another army of servants, cooks, carpenters and carters. Three thousand horses would be shipped over. The landing might be opposed, and so stores to feed the army for a month would be carried; for the horses alone there would be ship-loads of hay and grain.

Orm was involved in training the multinational force in how to obey commands in the Frankish tongue, and to respond to the bugles and horns. Orm was a foot-soldier and he concentrated on working with infantry troops. But he watched the cavalry training, as tightly knit teams of a dozen men wheeled across the chalky grass. Orm had seen the use of horses in Brittany. In their petty assaults on farmers the knights had never known defeat - but they had never been tested against a shield wall, and Orm was sceptical how much use they would be. But the cavalry was certainly an inspiring sight, that long Norman summer.

Meanwhile the invasion fleet was built and assembled. William’s advisors had calculated that nearly seven hundred ships would be needed. Most of these ships would have to be built from scratch. Norse and Danish shipwrights agreed on a design with broad beams and shallow draught, capable of crossing the ocean then navigating far upriver if necessary, and easily hauled ashore on the roughest beach. Some of the ships would be constructed with enclosed booths for the horses, like floating stables.

Woodmen, shipwrights and carpenters came from all across Europe to labour all summer with their saws, axes, adzes and bills, hammering together the ships. The Viking shipbuilders were the best, of course, their skills honed over centuries and passed down father to son. To supply this vast industry immense rafts of stripped logs were floated down the river arteries. It was said that fifty thousand trees were felled.

The great invasion was a massive undertaking that drained the resources of the whole duchy - and it all had to be paid for. William imposed quotas on his nobles: you ‘owed’ so many ships, so many infantrymen, so many horsemen. Even Odo had to provide a hundred ships. William made up shortfalls from his own coffers and the duchy’s treasury.

Orm began to see that the invasion was an extraordinary gamble. If it failed, Normandy would be left bankrupt and bereft of a generation of leaders. Its enemies, not least the king of the Franks, would surely pounce. But the Duke’s will never faltered.