The first Benedictine monks (although they were not called as such at the time) were those of Monte Cassino in the middle of the 6th century, living under the Rule just penned by St. Benedict himself. In time the Rule of Benedict became widely adopted. In the 9th century this happened on a grand scale when Charlemagne decreed that the Rule of Benedict was to be used exclusively by all monks and nuns throughout the Carolingian Empire. By the end of the 10th century, the Rule of Benedict was used almost exclusively throughout the Continent and England. This was the case until the development of new orders in the 11th century. At the time the monks were known by colors of their habits. The Benedictines were known as black monks, while the Carthusians and Cistercians were known as white monks.
Even though the Rule of Benedict had been so widely adopted, there was no formal union among the Benedictine monasteries. Each monastery was authonomous and there was no Order. Pope Innocent III changed this. The IV Lateran Council (1215) imposed a Cistercian-like form of governance upon all monastic houses. The Benedictine monasteries were to form regional alliances headed by presidents. The president was to do two things: meet regularly with the abbots and review the monasteries on a regular basis. These measures would encourage a certain degree of uniformity among the monasteries and also foster good monastic discipline. Innocent III was clearly interested in the health and longevity of this face of the Church. The English Benedictines complied promptly: in 1216 the English Benedictine Congregation was born. Eventually, other national groups would follow suite.
In order to exercise a certain degree of control over the many Benedictine Congregations, Pope Leo XIII united the Congregations into a Confederation known as the Order of Saint Benedict. The details are legislated in Summum semper of 1893. The brief provides for an Abbot Primate, headquartered in Rome at Sant'Anselmo. He has limited jurisdiction over the Congregations and individual abbeys, mainly in certain extraordinary circumstances related to disputes and discipline. The autonomy of the individual abbeys is preserved. Although the Abbot Primate's power is limited and his post is partly symbolic, he does serve as the primary communication link between the abbeys and the Holy See.
Today, the Benedictine Confederation encompasses 21 congregations with 381 monasteries and some 8400 monks. The English Benedictine Congregation has 13 monasteries with some 335 monks and 45 nuns.