Pope Urban II’s call to arms launched the First Crusade and galvanized recruitment across Latin Christendom, including key contingents from imperial territories such as Lorraine (then within the Empire’s sphere).
Godfrey of Bouillon, duke of Lower Lorraine, led a major force from the Empire’s western regions to Constantinople and onward into Anatolia, making the Empire’s nobility central to the crusade’s leadership coalition.
After Jerusalem’s capture, Godfrey of Bouillon (from Lorraine) became the city’s first Latin ruler (as advocate/defender rather than king), a defining outcome of the First Crusade and a touchstone for later imperial crusading ideology.
A major follow-on expedition to reinforce the crusader states included prominent participants from the Empire, such as Welf I of Bavaria; the campaign’s Anatolian disasters highlighted the risks of overland passage through Seljuk-controlled territory.
King Conrad III (ruler of Germany within the Empire’s political framework) led a large German host toward Byzantium, marking the first crusade led by a German king and a major imperial commitment to the Levant.
The German crusaders suffered a severe defeat by Seljuk forces near Dorylaeum during the Anatolian crossing, crippling Conrad III’s expedition and contributing to the Second Crusade’s overall failure.
A German contingent associated with Conrad III’s force was ambushed and shattered near Laodicea, further reducing imperial manpower and underscoring the vulnerability of crusader columns in Anatolia.
Emperor Frederick I Barbarossa set out overland with a large imperial army, representing the Holy Roman Empire’s most substantial direct expedition to the eastern Mediterranean during the crusading era.
Barbarossa drowned while crossing the Saleph (Göksu) River in Anatolia, a shock that fragmented the imperial expedition and sharply reduced German pressure on Saladin’s forces during the Third Crusade.
During the Siege of Acre, German merchants/crusaders from Bremen and Lübeck established a hospital to care for German-speaking pilgrims and fighters—an institutional seed that soon developed into the Teutonic Order, linking imperial society to the crusader states.
A substantial German force associated with Emperor Henry VI’s crusading project arrived at Acre; although Henry died before personally departing, the expedition briefly strengthened the crusader states and captured key coastal positions before many nobles returned amid an imperial succession crisis.
Frederick II’s repeated crusading vows—associated with his royal and imperial coronation contexts—became a long-running point of papal pressure and shaped the eventual imperial-led Sixth Crusade.
After Frederick II failed to proceed as planned from Brindisi amid illness and epidemic, Pope Gregory IX excommunicated him, setting up a crusade conducted under the unprecedented condition of an excommunicated emperor seeking results in the East.
Ignoring excommunication, Frederick II departed again for the Levant in summer 1228, carrying an imperial expedition whose strategy relied heavily on diplomacy and on support from the Teutonic Knights.
Frederick II reached Acre (the kingdom’s capital) in early September 1228, but faced resistance because of his excommunication; his limited coalition pushed him toward negotiated settlement rather than major battles.
Frederick II and Sultan al-Kāmil agreed to a truce that transferred Jerusalem (with negotiated arrangements over sacred spaces) and other territories to the crusader kingdom, demonstrating the Empire’s distinctive use of diplomacy to achieve crusading aims.
Frederick II entered Jerusalem in March 1229 following the treaty, symbolizing an imperial restoration of access and authority in the holy city without a decisive battlefield victory—an outcome praised by some and condemned by others in Latin Christendom.
Crusading participation and imperial expeditions from the Empire (1096–1270)
