What is the peculiarity of the military organization of the ancient Russian state?

In the Old Russian state, the military organization was represented by several types of troops. The whole army was commanded by the prince. He was the main commander and commander in battles and, like an ordinary soldier, participated in military campaigns. The squad was divided into junior and senior. The senior troops included professional warriors. Also, the army was divided into several groups. It included princely squads, boyar detachments and people’s militias from artisans, farmers and other people. Sometimes foreign mercenaries were employed.