In the second half of the 6th century BC. e. Persian kings from the Achaemenid dynasty created one of the greatest empires in world history. During the conquests of Cyrus II the Great (558−530 BC) and his successors, in the course of only about forty years the Persians conquered states and tribes over a vast area from Asia Minor to India. Unruly local populations were exterminated, maimed, or relocated to other areas of the Persian Empire. The Persian army was the most advanced in the entire ecumene, and after the conquest of Media and Babylonia it absorbed the military achievements of the Medes and Assyrians. The royal guard of the Achaemenids was called “immortals”, since its number always remained constant (10 thousand soldiers) - a retired guard was immediately replaced by a recruit. The Persians knew how to take fortified cities by storm, using siege engines, embankments and mines. The navy helped them carry out ground offensive operations, delivering soldiers and provisions. The Persians carefully planned their military campaigns, collecting information about the enemy with the help of intelligence services (“the king’s eye” and “the king’s ear”). A NEW BOOK by a famous specialist in the military history of ancient peoples, Doctor of Historical Sciences A. K. Nefedkin for the first time in Russian literature in all covers in detail the organization of the army of the Iranians of the early era, the Persians of the Achaemenid (VI-IV centuries BC) and Sasanian (III-VII centuries BC) eras: types of troops and their tactics, siege and defense, reconnaissance, methods of conducting campaigns as land and sea, customs associated with war, as well as a number of aspects of military ideology.