Medieval Frisia was the coastal area between the northwestern corner of Holland and the town of Bremen, whose inhabitants participated in nearly every crusade to the East, acquiring fame as freighters and marine fighters.
In the period of the crusades, Frisia consisted of a series of autonomous districts, each governed in a more or less communal way by a local elite, whose members considered themselves to be noble but rejected secular knighthood. As a consequence of its geophysical structure, the Frisian territory was partitioned between the four dioceses of Utrecht, Münster, Osnabrück, and Bremen, but its people were bound by a common language, laws, and a sense of origin that centered on the myth of Charlemagne granting the Frisians freedom of territorial lordship. In non-Frisian crusade sources, the Frisians are always treated as a collective. They traveled by ship and usually fought on foot, as their watery lands did not favor mounted combat.
During the First Crusade (1096-1099), some Frisians made up part of the pirate fleet of Guynemer of Boulogne that offered military and logistic support to Baldwin of Boulogne in Tarsos (mod. Tarsus, Turkey) in November 1097. As they are mentioned along with men from Flanders, Antwerp, and other parts of Gallia (Gaul), it is likely that they came from the neighboring territories of Zeeland or Holland, which still were regarded as Frisian up to 1100/1125. Frisian is also mentioned by the chronicler Fulcher of Chartres as one of the languages spoken in the Lotharingian contingent of the crusade army.
Frisian participation in the conquest of Lisbon (1147) during the Second Crusade (1147-1149) is recorded only in Frisian sources. The author of an itinerary of the 1217 expedition which brought Frisians to Portugal revived the memory of the Frisian hero Poptetus Ulvinga who had died at the siege of Lisbon siege seventy years before. If he really had been one of the leaders of a Frisian contingent, then it must have sailed with the Germans from the Weser area, who were led by the archbishop of Bremen.
From the Third Crusade (1189-1192) onward, the Frisians are more clearly distinguished in the sources. A false letter of Frederick I Barbarossa, Holy Roman Emperor, to Saladin (dated 1189/1190) mentions Frisians as part of a series of Western peoples whose mobilization is announced, and indeed two groups of Frisians from the northern coasts are known to have taken part in this crusade. The first squadron, of more than 50 ships, left Frisia in February 1189. At the mouth of the Rhine, it joined crusaders from Holland and Cologne and sailed to Dartmouth, where English and Flemish squadrons were gathering. Their main goal was the city of Acre (mod. ‘Akko, Israel) in Palestine, but the crusaders were persuaded by the Portuguese to assist in the capture of the Moorish stronghold of Alvor in the Algarve (16 June 1189). Thereafter the Frisians embarked again for the Holy Land, together with some Danes. A speedy voyage via Messina in Sicily, where they chose the Hainaut knight James of Avesnes as their commander, brought them to Acre in time to help the Franks close the ring around the Muslim- held city at the beginning of September. At the end of April 1189, a second fleet of 11 ships, probably from eastern Frisia, departed from Blexen near Bremen, sailing via England to southern Portugal, where the crusaders took part in the siege of Silves (September 1189). This small squadron can only be traced up to 17 October, when it sailed into Marseilles, but it is assumed that it, too, ultimately reached Acre. Eight years later another Frisian unit is reported to have left for the Holy Land; it is likely that it accompanied the north German fleet of Bishop Hartwig II of Bremen, which formed part of the Crusade of Emperor Henry VI (1197-1198).
More numerous were the Frisians who took the cross on the Fifth Crusade (1217-1221). Recruitment (at least for the archbishopric of Cologne) was organized by the papal delegate Oliver, master of the Cologne cathedral school, in collaboration with the abbots of many newly founded monasteries in Frisia. Helped by a series of miraculous signs in the sky during his campaign, this preacher managed to recruit 13,000 Frisian fighters according to his own estimation. They sailed with crusaders from Germany, England, and Holland, manning no fewer than 86 out of 200 ships. In contrast to the other nationalities, who decided to campaign in Portugal, the Frisians obeyed the strict orders of Pope Hon- orius III to sail directly to the Holy Land, but were delayed by bad weather, wintering in southern Italy. In April 1218 they set sail for Acre, where their fleet was chartered by John of Brienne, king of Jerusalem, to transport the crusader army to the Nile delta. The Frisians also served the Christian cause by constructing a siege machine on 2 cogs, with which they were able to capture the chain tower of the port of Damietta (25 August 1218). However, immediately after this feat of arms, the majority of the Frisians went home; a huge flood that caused thousands of casualties in Frisia soon after their return was blamed on the premature departure of these crusaders.
In 1224 Oliver of Cologne again preached the crusade in Frisia. Although he had less success on this occasion, a small Frisian fleet departed from the island of Borkum in the spring of 1227; its further adventures are unknown. Shortly afterward the bishop of Utrecht acquired massive support in the Frisian parts of his diocese for three successive crusade expeditions against the rebellious population of Drenthe (1227-1233). Some Frisians also participated in a similar political crusade against another neighboring people, the Stedinger, who had been declared heretics by the archbishop of Bremen (1234).
In 1247 the Frisians were called on by Pope Innocent IV and King Louis IX of France to join the latter’s crusade to the East (1248-1254), but the pope eventually allowed the Frisians to fulfill their vows in aiding William of Holland, king of the Romans, against the city of Aachen. By contrast, Frisians joined King Louis’s second crusade (1270-1272) in large numbers. On 18 April 1270, 50 cogs left Borkum, and although they were too late to sail from Aigues Mortes in France with the main fleet, they managed to arrive in Tunis shortly before the king died. According to the Frisian chronicler Menco, abbot of Wittewierum, the Frisians fought in a battle under the command of the king’s brother Charles I of Anjou, probably at El-Bahira. Like other nations in the crusader army, their group was decimated by an epidemic. The survivors left Tunis in September and sailed to Acre with 32 ships, only to discover that they could not be of any military importance there. With this expedition, Frisian crusade participation came to an end.
In late medieval Frisian historiography, the memory of heroic crusaders is a central theme, connected with the idea that the chosen people of Frisia had earned its freedom because of its achievements for Christianity. The mythical stories were most popular in West Frisian districts, which were longest able to resist the territorial expansion of neighboring lords.
Enthusiasm for the crusade is reflected in the relatively high number of establishments of the military orders in Frisia: the oldest foundations date to before 1240, and by 1300 there were twenty-one separate houses of the Order of the Hospital and three of the Teutonic Order. The Teutonic houses, situated west of the Lauwers, were organized in the provincial district of Utrecht. The one commandery of the Hospitallers in the same region also came under a Utrecht house (St. Catherine’s convent). All other Hospitaller establishments (situated in the modern Dutch province of Groningen and the German district of Ost- friesland) formed an administrative area of their own, the Bailiwick of Frisia, which came under the authority of the commander of Steinfurt in Westphalia. Peculiar to the houses of both military orders was the fact that they had no knight brethren. The wealthier establishments developed into either nunneries or convents of priests, some of whose members were active as parish ministers, while the poorer houses were peopled with lay sisters. The commanders were always priest brethren. This monastic structure can be explained by the character of the Frisian aristocracy, which lacked a knightly class from which knight brethren could otherwise have been recruited.
In the fourteenth century a series of conflicts broke out between the monastic communities and their respective provincial superiors on issues such as the recruitment of new members and the election of commanders. These were resolved by permitting the Frisian brethren autonomy in these matters. In the last quarter of the fifteenth century, the Hospitaller provincial commander at Utrecht and his Teutonic counterpart at Steinfurt both strengthened their grip on their Frisian houses by peopling them with non-Frisians and diminishing the number of lay brethren and sisters. In all of the Frisian lands, the Reformation brought an end to the houses of the military orders, first in the areas under the Lutheran counts of Eastern Frisia and Oldenburg, and later in the provinces of Friesland and Groningen, which in 1580 and 1594 respectively joined the Calvinist-oriented Republic of the United Netherlands.