In the middle of the eleventh century, a society of merchants from Amalfi in Italy, who made an annual journey to Egypt, received permission through repeated valuable gifts they presented to the local Caliph Mostaffan Billach and his ministers to build a special hostel for Western Christians near the Holy Sepulchre in Jerusalem, as well as a chapel for devotional exercises. Eduard L. Wedekind describes in this volume the history of the Order of St. John from its founding in the 12th century in Jerusalem to the development of the Grand Mastership in Sonnenburg during the 15th and 16th centuries in Prussia. The focus is particularly on the internal structures and constitution of the Order. The Verlag der Wissenschaften publishes historical literature by both well-known and lesser-known scholarly authors.