Defence in depth in order to retreat successfully, and they assume that the defender's morale will recover from the retreat. A possible early example of this came at the Battle of Cannae in 216 BC, when Hannibal employed this manoeuvre in order to encircle and destroy eight Roman legions, but that is disputed by some historians. Edward Luttwak used the term to describe his theory of the defensive strategy employed by the Late Roman army in the 3rd and 4th centuries AD. Later examples of defence in depth might be European hill forts and the development of concentric castles. In those examples, the
History of general anesthesia History of general anesthesia Attempts at producing a state of general anesthesia can be traced throughout recorded history in the writings of the ancient Sumerians, Babylonians, Assyrians, Egyptians, Greeks, Romans, Indians, and Chinese. During the Middle Ages, which correspond roughly to what is sometimes referred to as the Islamic Golden Age, scientists and other scholars made significant advances in science and medicine in the Muslim world and Eastern world. The Renaissance saw significant advances in anatomy and surgical technique. However, despite all this progress, surgery remained a treatment of last resort. Largely because of the associated pain, many patients with