Guiscard first takes centre stage in the power at Civitate in 1053 when the Normans defeated the papal forces of Italian and German allies (Book II: 122-256). William’s extensive description of the battle allows him to use his epic style with considerable zest and clearly demonstrates the episodic nature of his writing. His examination of this Norman victory indicates its significance as the point at which the Normans became a permanent fixture in southern Italy and its importance in Guiscard’s rise to dominance. The writing in this section of the poem is expansive, unlike the Gesta’s generally lean descriptions: William’s delight in wordplay and repetition is clearly evident here. In his description of Guiscard’s brilliance in battle, William of Apulia is using the set piece of Norman epic histories paralleling the decriptions of William at Hastings in the Gesta Guillelmi and the Carmen de Hastingae Proelio. Yet, in treating Robert as a ravaging beast, the Gesta signals its unease with the heroic conquerors and their aurocratic ambitions.
William’s analysis of Guiscard’s character shows him to be far more complex than the raging beast of Civitate. He can show generosity (Book II: 312-313) and kindness to the defeated (Book II: 335-359, III: 149-162, 326-330, 345-346). His eloquence matches his ambition (Book II: 298-307). But it is Guiscard’s volatility that seems to be his dominant trait: he can be compassionate one moment and brutal the next. Robert is an individual of many talents; he uses ‘ars’ as well as ‘arma’, craft as well as brute force. His strategic versatility marks him out as an archetypal Norman warlord who combines guile with cruelty. The allusion to the Odyssean agility of Guicard’s mind is an important liet-motif of the poem. Robert’s ruses come thick and fast and especially in his scheme to take a secure fortress (Book II: 232-254). The language of this passage echoes Dudo’s history where Hastings captures Luna through the same trick. However, while Dudo’s hero’s behaviour can be excused as he was a pagan Viking; the same cannot be said of Robert, a Christian Norman who had recently sworn fealty to the pope. The problem that William identifies is that Robert did not mature in this respect and remained a trickster to the end. This suggests the fundamental weakness of Robert’s rule in Apulia and Calabria: his failure to establish an effective system of governance other than his personal rule through terror and fear.
Despite this, William of Apulia drapes his hero in the epic trappings of ancient Rome. This is clear from his choice of verse over prose and of the archaic dactylic hexameters over the popular rhymed, acential verse that Malaterra occasionally introduces into his prose narrative. William wrote in verse because it could set the proper tone for an epic saga and because it linked the Gesta to the great works of classical poets. Like Dudo, William of Apulia uses classical models to subvert his ostensible aim of celebrating Norman heroes. The Prologue has allusions to ancient poets singing of their own heroes and William implicitly compares Norman successes and settlement in Italy with the experience of Aeneas and the Trojans. The tone shifts in the later books of the Gesta as Guiscard’s ambition provokes rebellion. The allusions shift from Vergilian echoes to Lucan and his Pharsalia, an angry indictment of the civil war that toppled the Roman Republic.
This shift signals William’s growing dissatisfaction with Guiscard’s ruthlessness and imperial ambitions. The Lucan parallels in Books IV and V reflect that Guiscard, like Julius Caesar at the Rubicon, reveals his imperial ambitions by going into forbidden territory. As Guiscard prepares for his expedition into the Byzantine heartland, he attracts ominous recollections of Lucan’s Caesar, openly a tyrant with no further pretensions to benevolent lordship. This can be seen in his response when Jordan of Capua signed a peace treaty with Henry IV of Germany (Book V: 118-119) and in the reluctance of conscripted Normans to fight the war. William of Apulia also introduces another hero to challenge Guiscard’s eastern campaigns in the person of Alexius Comnenus, Byzantine emperor from 1081. Certainly any hero needs a worthy adversary but the Gesta’s sympathethic picture of Alexius exceeds this necessity, even making Guiscard look foolish and inept in comparison. Around the millennium, Dudo found Vergil an appropriate vehicle for both honouring and satirising the Norman counts. A hundred years later, William of Apulia could look back over decades of despotic rule and find Lucan’s lens more apposite. Contemporaries, knowledgeable about Vergil and Lican would have deciphered the code and grasped William’s argument against the injustice of the Byzantine adventure and the ambitions of the Norman princes. The shift of poetic model from Vergil to Lucan parallels the Gesta’s transition from celebration to threnody.
The positive mood of the first three books culminates with William’s account of the war in Sicily and his enthusiasm for this just and Christian war highlights his disapproval of the attack on the Byzantine Empire. William implies that the divine will that authorised the wars in southern Italy and Sicily opposed and doomed Guiscard’s assault on the peoples across the Adriatic. This view complemented the interests of William’s patrons. Urban II sought a reunion of the churches following the schism of 1054 and a rapprochement with Alexius Comnenus. This followed the precedent of Gregory VII whose attempts to reunite eastern and western Christianity brought him into conflict with the rebellious Normans and the three-time excommunicated Guiscard. For Roger Borsa, his father’s Balkan adventure may have seemed a foolish diversion from consolidating Norman lands in southern Italy and it claimed Guiscard’s life before his son was capable of vigorous rule on his own.
William of Apulia’s Byzantine sympathies contrast with the negative views of Malaterra for whom the Greeks were ‘always a very treacherous people’ (Book II: 29) and with the scorn of Amatus of Montecassino. The Gesta deflates Guiscard’s justification for invasion and when he exhibits the pseudo-Michael at the siege of Durazzo he is humiliated when the citizens of Durazzo treat him with derision and laughter. This is a rare failure for Guiscard but foreshadows the ultimate failure of the campaign. Warfare still dominates the story but it now seems tarnished and less than glorious.
Like minor variations on a major theme, rebellions punctuate the Gesta. Soon after Melus enlists Normans in his rebellion, they are fighting among themselves over the spoils. (Book I: 148-152) and they repeatedly abandon one master for another (Book I: 318-327, 414-416). Tensions increase as the Hauteville brothers turn against each other with Humphrey and Robert almost coming to blows over the spoils from the conquest of Calabria (Book II: 310-313). Guiscard’s marriage to Sichelgaita rouses jealousy among the counts who plot her death (Book II: 444-450) and this eventually leads to open rebellion (Book II: 451-479). On Guiscard’s victorious return from Sicily, another rebellion breaks out led by Peter of Trani. William makes no attempt to whitewash Guiscard and paint the conspirators as culpable. He accords some legitimacy to their actions as justifiable resistance to an aggressive, absolute lord and Guiscard’s actions provoke the Norman lords to a massive rebellion in the late 1070s. Book III ends with Robert compelling the Normans to accept his lordship but this was not, and surely this was William’s intention, a comforting resolution of the problem: the subdued will lay low until a better opportunity presents itself.
There is a strong sense of hubris running throughout the Gesta and especially from Book III as the mighty tumble from the heights. Romanus Diogenes suddenly loses his imperial title (Book III: 91-92); Jocelyn languishes and dies in Guiscard’s prison (Book III: 139-141); but the most pitiful fall is Abelard’s who perishes as he plans a triumphant return to Italy to reclaim the lands Guiscard has taken (Book III: 659-667). The wretchedness of the human condition and the inevitable irony and cruelty of death is a recurrent theme. This may be the result of the ambitions of duke or warriors but often involves fickle fortune. William of Apulia follows the medieval tradition of invoking fortune as the cause of certain events despite its apparent clash with Christian doctrine. This reinforces William’s bleak tone especially in the last two books when the good luck that Guiscard had relished finally deserts him. With the beginning of the Balkan campaigns, the tide of fortune turns against Guiscard and ultimately, he too faces ruin.
This sense of melancholy builds to a climax in the lament at Guiscard’s death. Twice the Gesta reveals that Robert sails from Italy never to return (Book V: 140-142) leaving unfulfilled his plans to settle in Salerno. There is no eulogy for Guiscard as there was for his brother Humphrey (Book II: 273-280) and the Gesta confines weeping to two lines. It is the lamentation of Sichelgaita (Book V: 301-322) that dominates his death and her dirge foretells her own doom and that of her son and people without Robert’s protection. The denouement of Book V is chaos as Roger signals retreat from the Balkans and the Norman army, without Guiscard, falls apart and succumbs to panic and Guiscard’s body is almost lost in a storm that decimates the Norman fleet. Triumph is replaced by fear; order by chaos. With Guiscard gone and with no effective replacement, Sichelgaita recognises that the wolves are gathering (Book V: 513-515).
 The critical question is whether William modelled his verse directly on passages from Horace, Ovid, Lucan and especially Vergil or whether the epic episodes were not direct borrowings but a reflection of medieval traditions and language. Mathieu tends towards the latter position.
 Although the predominant classical influence in Books I-III is the Vergilian epic, there are clear and unsettling allusions to Lucan’s Pharsalia and Ovid’s Metamorphoses.