Answer: The Christian Church
Explanation: After the collapse of the Western Roman Empire, and the formation of smaller national states, or smaller kingdoms, which were often opposed, military commands were under the rule of kings, landowners, nobles. There was no central strong military command, and the soldiers themselves, knights often worked for the one who paid better. A feudal system was established in the so-called medieval period. The church strengthened and became more powerful, because it often associated with the rulers and offered its blessing, giving the divine mandate to the rulers, and in return received riches and royal support. The Church actually dominated the Middle Ages and the pope also had political, not just religious power. With the split of the Church in 1054, the Western Church was not weaker, it still had power, and the Eastern Church also had the influence in the Orthodox Empire.