One may be excused for the onset of fatigue at yet another history of the fall of the western Roman empire, standing as they do in serried rank, in every language, new ones each and every year. But one ought not to succumb to that lassitude, not in this case, because there is nothing else like it in the French language. Most new histories of the late empire are anything but new; indeed some of the best-selling British examples might as easily have been written a hundred years ago, so retrograde are their interpretations. The range of quality between the sublime and subprime is just as great in the German-language literature, and--as Italian and Spanish productions have improved dramatically over time--Francophone readers have been peculiarly ill-served. Apart from works of narrative vulgarization (Mussot-Goulard, Labouisse, etc), one must fall back on the classic works of Émilienne Demougeot, which for all their many virtues remain constrained by their post-War conceptual framework, and (still less happily) the syntheses of Michel Kazanski and Iaroslav Lebedynsky, the analytic foundation of which is hopelessly retrograde despite their relatively recent date. Indeed, only the work of Magali Coumert on Les origines des peuples can match the theoretical sophistication of the best German and Anglophone treatments of late antique barbarians, and it is a closely observed interpretative essay, not a narrative.  Whatever has accounted for this lamentable publishing phenomenon, it is now a thing of the past. Delaplace's fine study not only holds its field of one, but will surely do so for as long as Demougeot's De l'unité à la division de l'empire romain did in its day. 
The question for the Anglophone reader, then, is where Delaplace adds not merely to the French conversation but to the international one. Perhaps the single most important thing here is the authorial willingness to define terms and exercise a realistic parsimony of interpretation with the evidence. For instance, her exhaustive treatment of treaties and their related vocabulary (pax, foedus, deditio, amicitia) usefully demonstrates that the frequent scholarly attempts to normalize the semantic content of that vocabulary are completely untenable; so too is reading back a normative definition from Procopius and Jordanes into the fourth and earlier fifth century. Such observations are not wholly new, but actually applying their analytical insight to the narrative evidence exposes the role that fixed definitions of Roman treaties/foedera play in traditional narratives of Gothic history--thus producing a spurious aura of inevitability stretching from 382 to the settlement of some Goths in Aquitaine forty years later and on into the sixth century. In a similar vein, Delaplace correctly notes that Alaric and all the barbarian generals and condottieri of the late fourth and fifth centuries were primarily leaders of armies; their royal status was secondary, indeed often quite notional, and rarely a meaningful factor in their power. In this approach she strengthens Guy Halsall's demonstration that only Roman military office and magisteria constituted success for such people. To fall back on claims to royalty signified failure.
Perhaps the most insightful part of Delaplace's account of the early fifth century follows from the recognition that--whether or not you read Alaric's following, or those of other barbarian leaders of the time, in ethnic terms or instead as relatively heterogeneous mercenary armies--you cannot read them in terms of external diplomacy, or foreign foes. The more precise historical analogy is the late Roman Republic, when the Senate had to deal with rival armies loyal primarily to their generals rather than the state. Mutatis mutandis (for "Senate," read "imperial court"), the endless back and forth of 395 to 418 operated according to the same dynamic. Ethnic difference, still less "foreignness," are not what was at issue.
The book's systematic successes are in a similar vein. A ruthless refusal to retroject later evidence means that the Gothic settlement in Gaul is judged at its correct worth: there was nothing new about 418 that had not been at least implicit in the treaty of the king Wallia and the magister militum Constantius in 416. Wallia's (and then Theoderic I's) Goths were in effect a mercenary army, contracted by the Roman state because they were less likely to slip into the usurpation to which rebellious Gallic armies had long been prone. The Gothic zone of action effectively displaced the western Rhine limes south to the Loire, where, from Aquitaine, the Gothic army could operate in any direction necessary, against barbarians and potential usurpers alike. Thus, there was no kingdom of Toulouse for the better part of a century. There was a Gothic rex (who very rarely used that title) and there were sortes Gothicae, but there was no regnum till the fifth century had run its course.
Again, Delaplace has a firm grip on later fifth-century events. In particular she rejects the lionisation of the general Aëtius as "the last of the Romans," a sort of incomparable bulwark against the encroaching barbarian tides. Aëtius, she demonstrates, fundamentally weakened the Roman state, perpetuating constant rivalries in Gaul and Italy that militated against coherent policy. She shows how the "Gothic wars" of the 430s and 440s should not be read as a Roman defence against aggressive barbarian expansion, but rather as an extension of the civil war that brought Aëtius to power, the initial rivalry of Boniface and Aëtius, allied respectively with Theoderic and the Amal Berimond, was perpetuated in the next generation by Sebastianus (son of Boniface) and Witteric (son of Berimond), supported respectively by Theoderic and Aëtius. The peace of 439 is not a Romano-Gothic peace, nor a taming of the unruly federates by Rome, but rather a final settlement of two decades of rivalry: Sebastian was expelled by Theoderic, Witteric disappears from the pages of history (murdered, one imagines), and Aëtius married a daughter of Theoderic, having repudiated his second wife Pelagia, herself the sister of Berimond and widow of Boniface.
There is a great deal more good material along these lines, analysis of the aftermath of the Catalaunian Fields not in terms of Romano-Gothic rivalry, still less pro-Roman and anti-Roman factions at Toulouse (for such did not exist), but in terms of the endemic rivalry of potential heirs for the rank and privileges of their now dead father. The account of the 460s is again only partly read in terms of rival territorial or ethnic power centers, and more plausibly as Gallic factions attempting to profit by choosing one or another side in the now-constant Italian instability. The old story that Euric, in 470, turned on the empire to aggrandize his kingdom is rejected--he has not turned against the empire, but is rather a factional supporter of Anthemius and then Nepos against Ricimer and then Gundobad, with their puppet emperors. In the same light, one cannot talk about the Gothic "conquest of the Auvergne" and "Auvergnat resistance" (standard tropes of a Francophone scholarship still marked by the imaginative force of the Franco-Prussian and World Wars). One must instead realize that, from the moment he became a bishop, our main source Sidonius Apollinaris was a strong partisan of the Burgundian kings, and that what he portrays as devious and persistent Gothic expansion is the latest phase in the Gothic king's partisanship in the Italian civil wars, where the Burgundian Gundobad had succeeded Ricimer as the chief military power. For this reason, it is not till the treaty between Euric and Odoacer in 477--the latter acknowledged as the delegate of the Constantinopolitan emperor Zeno--that we can begin to talk of a regnum Tolosanum.
The book concludes with a more cursory survey of the period from 477-531, but here too, the guiding principles are correct. In particular, Delaplace considers the battle of Vouillé as a stage in the sorting out of post-imperial factions that characterizes the earlier sixth century, rather than as a caesura in Gothic history. Greater detail in this section would have been welcome, but that was not the author's primary goal. One would not have thought it possible to write a strikingly novel history of the last century of the western empire, but that is precisely what Delaplace has done. It is a grand accomplishment.
1. Magali Coumert, Origines des peuples: Les récits du haut Moyen âge occidental, 550-850 (Paris: Institut d'études augustiniennes, 2007).
2. Emilienne Demougeot, De l'unité à la division de l'Empire Romain 395-410: Essai sur le gouvernement imperial (Paris, 1951).