Deriving its legitimacy from Roman theories of public war, the examples of Scripture, and the identification of the Christian Church with secular powers, Christian holy war boasted an ancient pedigree. Long familiar with wars against external infidels attracting spiritual privileges, in the eleventh century the Western church extended the images and rituals of holy war to conflicts within Christendom as the church strove to define its legal, liturgical, and theological codes, as well as its relationship with the secular world. Impetus came from the radicals of the papal reform movement, who increasingly equated the universal church with the see of Rome. Ecclesiastical support for military activity centered on the protection and defense of the church, its clergy, and its property, exemplified by the Peace and Truce of God initiatives. Reforming popes, such as Leo IX in his attack on the Normans in southern Italy (1053), encouraged their troops to believe they were engaged in a holy pursuit, gaining remission of the penalties of sin. Pope Gregory VII (1073-1085), with his militia Sancti Petri (knighthood of St. Peter), insisted that fighting for the papacy was a penitential act, those killed being promised salvation. Such ideas owed less to Augustin- ian theories of just war than to the experience of militant Christianity and wars to defend the church since the eighth century. Both Anselm of Lucca’s Collectio Canonum (c. 1085), which included Augustinian just war texts but received little attention, and the description of the Christian warrior in De vita christiana (c. 1090-1095) by the extreme Gregorian Bonizo of Sutri focused on internal threats to the church by heretics and schismatics rather than wars against infidels.
By the time Pope Urban II preached the First Crusade in 1095-1096, holy wars against errant Christians, both in practice and in theory, occupied a familiar place in the arsenal of the papacy and its adherents, as, more widely, did the idea of divinely sanctioned violence in the culture of Western arms bearers. There is some modern debate as to whether these developments represented a clerical Christianizing of secular violence or, alternatively, a militarization of church teaching. Either way, by 1095 there existed a living tradition of Christian war against fellow Christians, a theory and practice familiar to veterans of the Investiture Wars who answered Urban’s call to the East.
The Jerusalem expedition of 1096-1099 was novel in its explicit association of pilgrimage and arms, its plenary indulgence, and its objective, but not in its penitential, or redemptive, dimension. Its features proved readily transferable to all theaters of Christian conflict, although its institutions only reached full coherence under Pope Innocent III (1198-1216). The legacy of the First Crusade encouraged overt demonstrations of holy war, as in peacekeeping in northern France or in papal opposition to the Norman kings of Sicily, while holy war against errant Christians received greater clarification in the great codification of canon law, the Decretum, attributed to the canonist Gratian of Bologna (c. 1140), where Causa 23 analyzed justified warfare within Christendom (although not war against pagans). When the thirteenth-century canonist Henry of Segusio (Hostiensis) insisted that the crusade within Christendom (Lat. crux cismarina) possessed greater urgency and justice than the overseas crusade (Lat. crux transmarina), he was not only condoning contemporary papal policy but also reflecting traditional attitudes.
Such transference of language, images, and institutions had been a fitful process: even by the fourteenth century not all wars fought against Christians on behalf of church or pope attracted the trappings of crusading: plenary remission of sins for combatants, even survivors, based on those granted to Jerusalem crusaders; the taking of vows and the receiving of the cross; the authorization of specific preaching; the offer of ecclesiastical protection and other temporal privileges; and, from around 1200, access to reserved clerical taxation, vow redemptions, donations, and legacies.
Indulgences were offered to those fighting for the pope against King Roger II of Sicily in the 1120s and 1130s (including a grant by the Council of Pisa in 1135 of the same remission as decreed at the Council of Clermont) and also against assorted heretics, together with their protectors and mercenary bands (Fr. routiers), in the 1130s and 1170s, but vows and the ceremony of taking the cross were absent. It has been argued that Pope Innocent III, fearful of losing control of Sicily, launched the first “political” crusade (a misnomer: like all wars, every crusade was, per se, political) in November 1199, against the freebooting adventurer Mark- ward of Anweiler, by offering the same indulgences as those given for campaigns in Outremer. Yet no evidence survives of preaching, giving of the cross, or other privileges in this context. Only with the promulgation of a crusade against the Cathar heretics of southern France and their Christian protectors in 1208 was the full apparatus of a war of the cross directed against Christians, in the Albigensian Crusade (1209-1229), its equality with the Eastern enterprises reinforced by the Fourth Lateran Council (1215).
Four long-term trends assisted this use of the crusade: (1) the desire to make the uniquely powerful crusade indulgence more widely available to the laity; (2) the configuring of the societas Christiana (Christian society) into a church militant, beset by evil, sin, and temporal enemies; (3) the inception of ecclesiastical taxation (in 1199) as the church became more fully incorporated into papal universalism; and (4) the acquisition, defense, and retention of a temporal Papal State in central Italy.
However, crusades against Christians fed off habitual responses to paid fighting and popular indulgences, and, unlike war with the infidel, allegiances were mutable. Given the papacy’s drive for exclusive uniformity of doctrine, dogma, and observance, charges of heresy and schism could readily be applied to any group that incurred official disapproval, especially those beyond the authority of the Inquisition: the Drenther peasants of the Netherlands (1228-1232), Bosnians opposed to Hungarian aggrandizement from 1227, and the Stedinger peasants of the Lower Weser (1232-1234), as well as the protectors of the Cathars during the Albigen- sian Crusade (1209-1229) or English rebels in 1216-1217 and 1265. As the tide turned against the Latins in their post- 1204 conquests in Greece, crusades were announced against Greek Orthodox Byzantines in 1231 and 1239, repeated into the fourteenth century, until the Ottoman threat imposed uneasy rapprochement.
Crusading lent physical force to excommunication as a political weapon. The main crusades against Christians centered on the independent temporal position of the papacy in Italy, the defense of the Papal States, and fears of territorial encirclement. Insecurity contradicted papal claims to temporal as well as spiritual plenitude of power. Only by maintaining their own secular state, free from invasion or rebellion, could popes feel safe in Rome. Crusades became major devices in several papally inspired campaigns: the struggle with the Staufen rulers of Germany and Sicily (1239-1269), the Wars of the Sicilian Vespers to restore Angevin control over the island of Sicily (1282-1302), the campaigns to secure papal interests in central and northern Italy during the evacuation of the Curia to Avignon (1309-1377), and attempts to resolve the Great Schism (1378-1417) by force.
The wars against the Staufen (Hohenstaufen) dynasty were designed to prevent territorial encirclement by Emperor Frederick II (1197-1250), ruler of Germany and, nominally, northern Italy, as well as the kingdom of Sicily, and his heirs; to assert control over Sicily, a papal fief; and to protect the Papal States, especially the March of Ancona and the duchy of Spoleto. A fundamental lack of trust in what Pope Urban IV called a “viper race” fueled the tenacity with which the Staufer were pursued by Popes Gregory IX (1227-1241), Innocent IV (1243-1254), Alexander IV (1254-1261), Urban IV (1261-1264), and Clement IV (1265-1268).
Although earlier campaigns, such as that led by John of Brienne in 1228-1230, had been funded by church taxation, and Frederick II had finally been excommunicated in March 1239, only in the winter of 1239-1240 did Gregory IX call for a formal crusade against the emperor. The anti-imperial Lombard League had been heavily defeated in 1237; Frederick’s forces were threatening Rome, where support for the pope remained fickle. By raising the stakes, Gregory could hope to stiffen local support but also mobilize a larger coalition in northern Italy and Germany. The apparatus of crusading emphasized a shared identity across political, social, and geographic frontiers; added powerful spiritual inducements to recruitment; and, crucially, permitted any antiimperialist coalition to be funded by church taxation. The crusade, renewed in 1240 and 1243, was preached chiefly in northern Italy and Germany, where papal anti-kings were established, first Henry Raspe of Thuringia, then William of Holland. Although hard to quantify, the political effect of these crusades, supported by the ringing endorsement of the First Council of Lyons (1245), lent a measure of cohesion and additional finance to the struggle against Frederick II.
On the emperor’s death, crusades were renewed against his son and successor King Conrad IV (1250-1254) in Germany and Frederick’s illegitimate son, Manfred (d. 1266), regent of Sicily. From the mid-1250s, the focus fell on southern Italy and Sicily. In 1255, Alexander IV persuaded King Henry III of England to accept the crown of Sicily on behalf of his second son, Edmund, hoping to add the resources of a secular kingdom to those of the church. Although English involvement proved abortive, Alexander’s idea of hiring a secular prince to attack Manfred (king of Sicily since 1258) was revived by Urban IV and Clement IV, who secured the services of Charles I of Anjou (d. 1285), a younger brother of King Louis IX of France. In a lightning campaign in the winter of 1265-1266, Charles of Anjou defeated and killed Manfred at the battle of Benevento in February 1266. Two years later, Charles consolidated his position by his victory at Tagliacozzo (August 1268) over Conradin, Conrad IV’s son, whom he subsequently executed in Naples (October), the last male member of the Staufen dynasty.
In the wake of the anti-Staufen wars, crusading became habitual. Crusades were launched in 1255 against Ezzelino and Alberic of Romano, in 1263 against Sardinia, and in 1263 and 1265 against English rebels. Italy still provided the most active arena. Following the Sicilian rising against Charles I of Anjou in 1282 (the so-called Sicilian Vespers) and the annexation of the island by King Peter III of Aragon, husband of Emperor Frederick II’s daughter Constance, a new crusade was promulgated in January 1283, culminating in the invasion of Aragon in 1285 by Philip III of France, which ended in retreat and complete failure. When Frederick II of Sicily (1296-1337), a younger son of Peter III, defied his elder brother James II of Aragon (1291-1327) by retaining control of Sicily despite a papal- Aragonese agreement in 1295 to surrender the island to the Angevins, another round of crusading ensued. This round ended only with the treaty of Caltabellota in 1302 between Frederick and the new papal claimant to the island, Charles of Valois, younger brother of Philip IV of France (1285-1314), which left Sicily in Aragonese hands. There were no more crusades against Sicily.
In the fourteenth century, Italian battle lines became fragmented. Twice attempts were made to reassert imperial claims in the peninsula by the German monarchs Henry VII (1310-1313) and Ludwig IV (1328-1330), the latter provoking a crusade against him for his pains. In general popes applied crusades to more local enemies, as with Boniface VIII (1294-1303) dealing with his rivals the Colonna family in 1297-1298, the suppression of the populist heretical movement of Fra Dolcino in Piedmont (1306-1307), or preventing Venetian control of Ferrara (1309-1310). The signori (military lords of cities) of Lombardy, Tuscany, and central Italy tended to be antipapal Ghibellines, prominently the Visconti of Milan; Florence and Naples tended toward the Guelph (i.e., pro-papal) side. Self-interest, not principle or faith, determined action: in 1334 Guelph Florence combined with its rival Milan to thwart papal plans to create a new Lombard puppet state.
Major campaigns over the Papal States were organized by cardinal-legates, notably Bertrand du Poujet after 1319 and Gil Albornoz after 1353, with crusades instigated in 1321 against Milan and Ferrara; in 1324 against Milan, Mantua, and rebels in Ancona; in 1354 against Cesena and Faenza; and against Milan once more in 1360, 1363, and 1368. In 1357, a new element was introduced by the crusade directed at the mercenary company of Conrad of Landau, other such companies (Fr. routiers) being targeted in 1361 and 1369/1370. Local and regional in objective, preaching, recruitment, and effect, these crusades allowed popes to spend huge sums on their Italian ambitions, while elsewhere they were reluctant to convert secular conflicts into holy wars, as in the case of French designs on Flanders or of the Hundred Years’ War (1337-1453).
During the Great Schism (1378-1417), crusades were launched by the Roman pope Urban VI against his rival at Avignon, Clement VII (1378); both sides lent crusade status to continuing succession wars in Naples: in 1382 by Clement VII, and in 1411 and 1414 by John XXIII. In 1383, a campaign against Flanders launched by Henry Despenser, bishop of Norwich, gained funds and popular support by being granted the status of crusade by Urban VI. For the English government, this was a cheap, if in the event dismally unsuccessful, way of pursuing the war against the French. John of Gaunt’s attempt to install himself as king of Castile in 1386 also attracted crusade bulls.
Increasingly, however, the military solution to the Great Schism lost appeal, not least because neither side had access to adequate church funds to sponsor large armies. The experience of the Italian wars of the fourteenth century combined with that of the Great Schism to dissuade popes after 1417 from using the crusade to defend the Papal States, perhaps a retrospective recognition of futility and the damage they caused to the standing of both papacy and crusade. Only the bellicose Julius II (1503-1513) revived the tradition of crusading in Italy, as well as granting crusading status to the French war of Henry VIII of England in 1512.
By contrast, where Wars of the Cross did appear more appropriate, there existed no hesitation. Thus there were several crusades fought against the Hussites of Bohemia (1420, 1421, 1422, 1427, 1431, 1465-1471), and another planned (1428-1429). The Reformation led to a brief, fleeting revival of crusade schemes against Roman Catholic enemies of the papacy, as well as the new schismatics and heretics, such as Henry VIII of England in the 1530s and Elizabeth I in the last years of the sixteenth century, when Spain’s attack and the Roman Catholic opposition in Ireland both became associated with crusading.
That crusading should become involved in wars against Christians was inevitable, given the pre-1095 history of holy wars within Christendom. That such an application only became habitual in the thirteenth century reflected the greater coherence of crusade institutions after the end of the twelfth century, as well as the enhanced bureaucratic and financial efficiency of the system of ecclesiastical taxation upon which such enterprises depended for their operation and appeal to military commanders. The simultaneous consolidation of the theology of indulgences aided recruitment to a cause that offered the greatest remission of sins possible, even though idealism alone cannot explain how armies were raised for these (or for any other) crusades. Holy war against Christians suited prevalent cultural attitudes that demanded formal religious sanction to secular behavior, hence the eccentric phenomenon of crusades against crusaders: in 1240, the imperialist dean ofPassau in Bavaria publicly preached the cross against the papal legate; in 1263-1265, Simon of Montfort explicitly associated his rebellion against King Henry III of England with a crusade; even in 1215 such a conflict occurred, when Robert FitzWal- ter, a leader of the opposition to King John, who had just taken the cross, called himself Marshal of the Army of God.
From the thirteenth century onward, papal wars against Christians attracted controversy. Victims and enemies naturally complained. Crusades against Christians could seem tawdry rackets, distracting from the higher call of the Holy Land. In the thirteenth century, many otherwise sympathetic to crusading opposed papal wars in Italy: clergy resentful at taxation, English and French nobles reluctant to commute their vows in the 1230s and 1240s, citizens of Lille in 1284, and Florentines who refused to allow their crusade legacies to be diverted. The papalist Hostiensis noted that popular opinion in Germany preferred the crusade to the Holy Land. Those eager to see crusading as a means of moral and religious regeneration tended to look to wars against heretics and infidels, not fellow Christians, which, in the fourteenth century, attracted limited international approval.
While popes such as Innocent IV, Clement IV, Boniface VIII, and John XXIII promoted wars against Christians, others, such as Gregory X (1271-1276) and Nicholas IV (1288-1291), pursued peace to achieve a new Eastern expedition. The Curia could recognize the potential unpopularity of crusades against Christians: in 1246 Innocent IV insisted that his order to his legate to stop preaching the Holy Land crusade in order to facilitate the promotion of the crusade against the Staufen should be kept secret. The concurrence of numerous crusade appeals with different objectives caused a degree of confusion, duplication, and contradiction of effort.
While popes and their apologists insisted that the anti- Staufen and Italian crusades were necessary prerequisites for any successful campaign in the East, others, such as the Venetian crusade propagandist Marino Sanudo (d. 1343), argued instead that they constituted major impediments to the recovery of the Holy Land. The gradual loss of Outremer coinciding with the intensification of crusading in Italy struck some as reprehensible. However, successive popes managed to find enthusiasts for their campaigns, eager to pursue secular warfare with spiritual benefits and church funding. It is hard to blame the crusades against Christians as single-handedly undermining support for the concept of Wars of the Cross or for papal authority in the West; John Wyclif’s famous attack on Despenser’s Crusade in 1383 formed part of a much wider critique of a church palpably in crisis over the Great Schism. Criticism of papal bureaucracy, corruption, and bellicosity embraced the Italian crusades but was hardly defined by it. There is no such thing as neutral public opinion, but it is hard to detect either majority condemnation or majority approval. Papal crusades against Christians, while producing major successes, such as Charles of Anjou’s victory, failed to secure papal territory. By the early fifteenth century, with papal temporal plenitude of power compromised by the growing assertion of national ecclesiastical autonomy, crusades against Christians, appearing at worst objects of derision and at best irrelevant beyond the regional conflicts to which they were still applied, were abandoned, rather as poor business than as ideologically corrupt.