I once asked a great medievalist, who had written on Raoul Glaber and the heresies and paradigmatic cognitive shifts that emerged suddenly in the early new century/millennium, why he never looked at the issue of the apocalyptic year 1000. "You know, as a graduate student I wanted to, but my advisor told me, don't open that can of worms." He might better have said, that hornet's nest, because if one pokes around in there, one meets, as Michelet did from Ferdinand Lot, and I did from Sylvain Gouguenheim and Dominique Barthélemy, with vigorous, indignant, hard-hitting denial, roundly applauded by colleagues. 
Apparently, it violates some hard-wired medievalist conviction to suggest that the denizens of an entire generation of Western culture acted as if they were participants in the End-Time drama--whether they believed that this apocalyptic transformation would lead to the millennial kingdom on earth, or the End of the world entirely. No, it seems, leaders of the past (clerical and secular) kept their sangfroid in the face of (what to those of future, hindsight-endowed generations appeared to be) ludicrous prophecy. Augustine, historians have assured us, was the "true conscience of Christianity," who guided his generation through "the dangerous thinking" at the time of the fall of Rome, and established the dominant orthodoxy in which neither apocalyptic beliefs nor millennial ones had a significant place. Up until a generation ago, most historians thought there was no millennialism between Augustine and Joachim of Fiore, and up until two generations ago, most medievalists thought Joachim was an insignificant thinker who would harm the reputation of any scholar foolish enough to consecrate her time to his study.
So when James Palmer set out to write a book on The Apocalypse in the Early Middle Ages, which would cover the period from the fall of Rome up to Y1K as he calls it, he was, at the very least, opening several cans of worms, in particular the two other "millennial" dates that preceded 1000 in Christian traditions of dating the apocalyptic advent of the messianic kingdom of the saints--das tausandjähriger Reich--to the end of the sixth millennium since creation. According to chronologies that variously calculated the number of years from creation, the year 6000 came twice within this book's purview, in 500 (Y6K^I), and in 801(Y6K^II). While a few historians have made much of this tradition of millennial calculation,  no medievalist has yet to give a book-length treatment to the range of these dates, and no historian of either the "Fall" of Rome or the Carolingian imperial experiment has integrated this into their analyses.
Palmer does his best to strengthen the anti-apocalyptic (Augustinian) reading of history. For him the changes in calculation of the age of the world derive not from a desire to avoid facing an apocalyptic year 6000, but rather from "scholarly concerns."
Unpacked, this question mal posée--as if the scholarly drive and apocalyptic agenda were mutually exclusive  --sufficiently muddies the waters so that if historians wish to continue writing the biographies of men like Theodosius and Clovis, or Charlemagne and Alcuin, or Otto III, Aethelred, and Robert, with no reference to the possibility that they lived in an apocalyptic generation, they can do so comfortably.
Ironically, but consistently, experts in computus and chronology tend to promote the most non-apocalyptic/a-millennial versions of their subject.  Hence if one might consider Palmer's knowledge of both chronology and computus as one of his great strengths, his understanding of apocalyptic dynamics, including their relationship to chronological discussions, constitutes one of his weaknesses. He discusses Augustinian eschatology as a regnant norm: commentaries on Revelation produced a perception of eschatology in which "it did not matter if the end was imminent or not." The expanded role of this de-apocalypticized spirituality (apocalypse here meaning sense of imminence), produced a "politicized apocalyptic discourse in the direction of reform and combatting heresy." (105)
Alternatively, Palmer emphasizes the predominance of a sense of "'psychological imminence' rather than 'chronological imminence'" [italics mine], that favors penitential attitudes, and institutionally acceptable forms of apocalyptic reform. He ends up with so spiritualized a notion of apocalyptic, however, that he can lump personal sense of Judgment together with collective forms. "The difference," he notes, "between what would happen to an individual if they [sic] died the very next day, and what would happen to them if the world ended in a non-millenarian scenario, is quite minimal: they would be judged." (14-15)
On this abstract and solipsistic plane, perhaps there is no difference; but the magic of apocalyptic moments is the collective anticipation of simultaneous public Judgment for all mankind--the quick and the dead! The final reckoning takes place "before the eyes of all living creatures." Apocalyptic moments, in this context, differ drastically from individual, solitary experiences of imminent Judgment. Indeed, far more unites apocalyptic believers whether they are part of a "purely" millennial movement (messianic era to begin now), or "purely" eschatological one (Last Judgment at End of the World). All those swept up in apocalyptic time, share the sense that history hangs on the hinge of salvation, and "we" are the generation chosen to live at that cosmic culmination and turning point.
Palmer gives this possibility short shrift. Instead, despite an occasional acknowledgment that 'psychological' and 'chronological' imminence need not be mutually exclusive phenomena, Palmer almost always frames the issues in binaries, and never explores the possibility that the two can combine to create mega-apocalyptic moments. (The formula rather than appears over a dozen times in the book.) Thus he insists that chronological changes arose from "factors divorced from apocalyptic speculation--Easter calculations, scholarly enquiry into chronology." (17)
And yet, one might suspect that the divorce is of his doing. The patterns of intensification of chronological and computus work over the centuries, the questions asked, and the successful answers given to how old the world--i.e., the pulse of the most lively and sustained "early medieval" science--maps nicely over a map of apocalyptic points-forts (at the approach of Y6K^I, Y6K^II, Y1K^I and Y1K^II). Weaving in a passion for computus and the linking of computus and chronology hardly negates the pattern. The alleged "divorce" Palmer invokes may actually mask a passionate relationship between "scholarly accuracy" and chronological imminence.
When he writes epigrammatically, "Prophecy could never fail--it could only be misunderstood" (15), Palmer looks only at the long-term trends and not at the immediate (and rapidly disproven) experience. Prophecy--including chronological prophecy--failed repeatedly in the early Middle Ages. And only out of deep and deeply effecting cognitive dissonance at that failure did apocalyptic discourse, including Palmer's "moral apocalyptic," rebound and reassert itself, retargeting its expectations into the future, its scenarios, its rhetoric, its calculations.
Having homogenized before and after (little anticipation, little disappointment), Palmer misses the meaning of his own data. Carolingians in 809 took AD as certain and wondered about the age of the world now that 6000 had passed a second time in three centuries (144); but at the approach of 1000, for the first time, people began to question AD's accuracy (190-92). Their concerns for accuracy sharpen the closer the apocalyptic advent approaches.
Instead Palmer sees "attempts soaked in scholarly enquiry and self-consciousness rather than an exercise in the suppression of a dangerous date" [italics mine] (100). As a result, he can only respond to Johannes Heil's subtle analysis of the 9th century Carolingians' cognitive dissonance at the passage of Y6K^II,  by repeating his dismissive mantra: "But, as we saw at the end of Chapter 5, this can make too much of Y6K and not enough of psychological imminence and imperial apocalyptic" (161). Might one not sooner view these scholarly attempts as soaked in apocalyptic preoccupations? Might it not be appropriate for an historian of apocalyptic and millennial developments in the early middle ages, when he writes that an "apocalyptic battle [in the Carolingian court] came to a head in the last decade of the eighth century (154), to also mention that it was also the last decade of the sixth millennium (5990s)?
Nor is chronological the only form of early medieval millennialism Palmer plays down. He deals similarly with the imperial variant, or the belief that a salvific world emperor would inaugurate the messianic era. In chapter four, Palmer discusses the manuscript career of the Apocalypse of [Pseudo-]Methodius, a millennial text that responded to the military success of Islam in its first century with a prophecy about a victorious Christian "Last Emperor" who would inaugurate a long period of supernatural earthly peace. Written in the late seventh century in Syriac, it was rapidly translated into Greek and then Latin. Four Latin copies survive from the eighth century (5900s AM II), and one variant even corrected the date AM^I used in the original text to bring it in line with the prevailing chronology of the West, AM^II).
This text and its later derivatives, like Adso's On the Antichrist, and the Sybilline Oracles (192-200), would have an immense impact on the West in subsequent centuries, reviving a bond between empire and apocalypse that Augustine had tried so hard to rend asunder.  How quickly did it spread in the 8th century? Could Charlemagne have believed that he was Methodius' prophesied, Last, messianic emperor? Could he have fallen prey to what Palmer calls the "Last Emperor schtick" (204)? Could his populus Christianus have believed that they were witnessing the long-awaited advent of the messianic age?
Not in Palmer's estimation. He locates Methodius' foyer in a monastic "intellectual environment away from the 'frontline' defense of society or political counsel." (128) In his mind, "moral eschatology" in the 8th/60th century trumped, rather than shared the apocalyptic stage, so amply set by chronology, with all other comers. Instead of seeing each variant as mutually reinforcing the apocalyptic thinking of all--popular, imperial, monastic, clerical, warrior--he splits among different strands. "Eschatology and apocalypticism," Palmer assures us, thrived on "immediate personal experience more than the date in abstract" [whatever that means, italics mine] (145).
Ironically, although he quotes one German historian disapprovingly for saying "I cannot believe that Charlemagne had anything to do with apocalyptic" (13), Palmer, in the end, has the same difficulty. He can imagine a Charlemagne and court busily engaged in a reform movement that used apocalyptic rhetoric in the service of sound political goals (ch. 5), but even though he will entertain the possibility that Otto III fell for the schtick, he barely mentions that possibility for Charlemagne (139). The imperial coronation taking place at the advent of 6000, a date no source mentions openly, was therefore coincidental. Indeed, Palmer argues that Carolingian scribes overlooked the advent of 6000 due to the work of scholars pursuing other matters:
Ultimately, the book ends up hoist on the petard of its own argument. Examining the material over the centuries, convinced that chronology did not have much of a role in apocalyptic discourse, Palmer essentially makes the bizarre argument that it's not, as earlier "anti-terrors" historians had insisted, that apocalyptic is nowhere in the dossier, it's everywhere; hence it has nothing particular to do with the advent and passage of these millennial dates. As a result, rather than the traditional image of a largely un-apocalyptic, Augustinian period, Palmer paints the opposite picture of his centuries:
A generation ago, that was historiographical heresy. Peter Brown scarcely mentioned such matters in his paradigm-setting, World of Late Antiquity.
The book concludes with a chapter on "The year 1000 and other apocalypticisms," by which Palmer means other, presumably independent, triggers to apocalyptic expectation like imperial apocalyptic, or fear of outside invaders, or social unrest. Here he must address the "apocalyptic year 1000" question. Presumably much of his earlier work dismantling the apocalyptic significance of dates, prepares him to play down the role of 1000 in the minds of contemporaries. But honest historian that he is, he cannot engage in outright denial.
Apocalyptic thinking as a way to handle crises that could come at any time?--yes. Apocalyptic thinking provoked by the advent of 1000?--not so much.
Palmer's treatment of the period, with its exceptional behavior--from penitential kings across the boards, to pilgrimage, heresy, mass penitential assemblies that mutate into a peace councils--becomes an exercise in begrudging concession. Rather than see the pervasive clerical apocalyptic discourse that he finds around 1000 as addressing and adding to a general apocalyptic intensity shared by everyone, he argues in binary dichotomies: "Apocalyptic fears were not the preserve of the frenzied masses but rather of their critics" (221).
On the subject of the Peace of God, and the mass gatherings in open fields, where clerical and monastic, popular and hierarchical, millennial and apocalyptic strains of all kinds gathered, Palmer reaches the height of his "give and take" rhetoric, where concession to the apocalyptic thesis gets an immediate down-grading:
In the end one gets a sense that an honest Augustinian historian, having chosen to tackle a period previously considered sparse in apocalyptic and millennial material, found himself forced by the evidence, no matter how he turned it, to acknowledge the pervasive role of apocalypticism and even millennialism throughout the period. But like Pharoah's servants preparing Joseph for presentation in court, he had to clean it up, shave off the embarrassing aspects of disproven chronological calculation, megalomanic royal pretensions, and popular millennial enthusiasm, and present to the larger historical profession an 'acceptable' apocalyptic discourse about penitential spirituality and institutional reform. As such, it's a distinct improvement over past efforts to just bury the subject, but still a long way from the kind of creative historiographical recreation this long and tumultuous period deserves.
1. Ferdinand Lot expresses sheer disgust for Michelet's wild rantings (divagations échevelées), "Le mythe des terreurs de l'an mille," (1947) in Recueil des travaux historiques de Ferdinand Lot (Geneva, 1970, vol 3, pp. 398-414). On Sylvain Gouguenheim's critique of my work, see his Les fausses terreurs de l'an mil: Attente de la fin du monde ou approfondissement de la foi (Paris, 1999); Barthélemy, L'an Mil et la Paix de Dieu (Paris, 1999). See the comments of Jonathan Jarrett in response to a talk that dismissed the importance of apocalyptic calculations and millennial movements: .
2. Juan Gil, "Los terrores del año 800," in Aetas del Simposio para el estudio de los codices del 'Comentario al Apocalipsis' de Beato de Liebana (Madrid, 1978), pp. 217-47; Richard Landes, "Lest the Millennium be Fulfilled: Apocalyptic Expectations and the Pattern of Western Chronography 100–800 CE," in The Use and Abuse of Eschatology in the Middle Ages, ed. Werner Verbeke, Daniel Verhelst, and Andries Welkenhuysen (Leuven, 1988), 137-211; and "The Fear of an Apocalyptic Year 1000: Augustinian Historiography, Medieval and Modern," Speculum 75 (2000) 97-145; Wolfram Brandes, "'Tempora periculosa sunt': Eschatologisches im Vorfeld der Kaiserkrönung Karls des Grossen," in Das Frankfurter Konzil von 794: Kristallisationspunkt karolingischer Kultur, ed. Rainer Berndt, 2 vols. (Mainz, 1997) vol. 1, pp. 49-79.
3. Same either-or, question mal posée in the subtitle of Gouguenheim's title, as if fears of the Judgment Day did not deepen the faith…
4. See, for example, William Adler's Time Immemorial: Archaic History and Its Sources in Christian Chronography from Julius Africanus to George Syncellus (Washington, 1989), which manages in its 250 pages, to mention the sabbatical millennium once in the text and once in a footnote.
5. Johannes Heil, "'Nos nescientes de hoc velle manere'--'We Wish to Remain Ignorant about This': Timeless End, or: Approaches to Reconceptualizing Eschatology after A.D. 800 (A.M. 6000)," Traditio 55 (2000): 73-103.
6. Robert Marcus, Saeculum: History and Society in the Theology of St Augustine (Cambridge, 1970).