This story illustrates many points in the character of William and of his time. His will is not to be thwarted, whether in a matter of marriage or of any other. But he does not hurry matters; he waits for a favourable opportunity. Something, we know not what, must have made the year 1053 more favourable than the year 1049. We mark also William's relations to the Church. He is at no time disposed to submit quietly to the bidding of the spiritual power, when it interferes with his rights or even when it crosses his will. Yet he is really anxious for ecclesiastical reform; he promotes men like Maurilius and Lanfranc; perhaps he is not displeased when the exercise of ecclesiastical discipline, in the case of Malger, frees him from a troublesome censor. But the worse side of him also comes out. William could forgive rebels, but he could not bear the personal rebuke even of his friend. Under this feeling he punishes a whole body of men for the offence of one. To lay waste the lands of Bec for the rebuke of Lanfranc was like an ordinary prince of the time; it was unlike William, if he had not been stirred up by a censure which touched his wife as well as himself. But above all, the bargain between William and Lanfranc is characteristic of the man and the age. Lanfranc goes to Rome to support a marriage which he had censured in Normandy. But there is no formal inconsistency, no forsaking of any principle. Lanfranc holds an uncanonical marriage to be a sin, and he denounces it. He does not withdraw his judgement as to its sinfulness. He simply uses his influence with a power that can forgive the sin to get it forgiven.

While William's marriage was debated at Rome, he had to fight hard in Normandy. His warfare and his negotiations ended about the same time, and the two things may have had their bearing on one another. William had now to undergo a new form of trial. The King of the French had never put forth his full strength when he was simply backing Norman rebels. William had now, in two successive invasions, to withstand the whole power of the King, and of as many of his vassals as the King could bring to his standard. In the first invasion, in 1054, the Norman writers speak rhetorically of warriors from Burgundy, Auvergne, and Gascony; but it is hard to see any troops from a greater distance than Bourges. The princes who followed Henry seem to have been only the nearer vassals of the Crown. Chief among them are Theobald Count of Chartres, of a house of old hostile to Normandy, and Guy the new Count of Ponthieu, to be often heard of again. If not Geoffrey of Anjou himself, his subjects from Tours were also there. Normandy was to be invaded on two sides, on both banks of the Seine. The King and his allies sought to wrest from William the western part of Normandy, the older and the more thoroughly French part. No attack seems to have been designed on the Bessin or the Cotentin. William was to be allowed to keep those parts of his duchy, against which he had to fight when the King was his ally at Val-es-dunes.

The two armies entered Normandy; that which was to act on the left of the Seine was led by the King, the other by his brother Odo. Against the King William made ready to act himself; eastern Normandy was left to its own loyal nobles. But all Normandy was now loyal; the men of the Saxon and Danish lands were as ready to fight for their duke against the King as they had been to fight against King and Duke together. But William avoided pitched battles; indeed pitched battles are rare in the continental warfare of the time. War consists largely in surprises, and still more in the attack and defence of fortified places. The plan of William's present campaign was wholly defensive; provisions and cattle were to be carried out of the French line of march; the Duke on his side, the other Norman leaders on the other side, were to watch the enemy and attack them at any favourable moment. The commanders east of the Seine, Count Robert of Eu, Hugh of Gournay, William Crispin, and Walter Giffard, found their opportunity when the French had entered the unfortified town of Mortemer and had given themselves up to revelry. Fire and sword did the work. The whole French army was slain, scattered, or taken prisoners. Ode escaped; Guy of Ponthieu was taken. The Duke's success was still easier. The tale runs that the news from Mortemer, suddenly announced to the King's army in the dead of the night, struck them with panic, and led to a hasty retreat out of the land.

This campaign is truly Norman; it is wholly unlike the simple warfare of England. A traitorous Englishman did nothing or helped the enemy; a patriotic Englishman gave battle to the enemy the first time he had a chance. But no English commander of the eleventh century was likely to lay so subtle a plan as this, and, if he had laid such a plan, he would hardly have found an English army able to carry it out. Harold, who refused to lay waste a rood of English ground, would hardly have looked quietly on while many roods of English ground were wasted by the enemy. With all the valour of the Normans, what before all things distinguished them from other nations was their craft. William could indeed fight a pitched battle when a pitched battle served his purpose; but he could control himself, he could control his followers, even to the point of enduring to look quietly on the havoc of their own land till the right moment. He who could do this was indeed practising for his calling as Conqueror. And if the details of the story, details specially characteristic, are to be believed, William showed something also of that grim pleasantry which was another marked feature in the Norman character. The startling message which struck the French army with panic was deliberately sent with that end. The messenger sent climbs a tree or a rock, and, with a voice as from another world, bids the French awake; they are sleeping too long; let them go and bury their friends who are lying dead at Mortemer. These touches bring home to us the character of the man and the people with whom our forefathers had presently to deal. William was the greatest of his race, but he was essentially of his race; he was Norman to the backbone.