Author(s): Maha A Elbadry1 , Mary M Merrill1 , Meng-Meng Ma2 , Mai-Juan Ma3 , Jia-Hai Lu2 , Wu-Chun Cao3 and Gregory C Gray1
Since ancient times, one of the chief reasons people banded together was for the purpose of defending themselves against threats to their safety and well-being. Protective measures have taken many forms over many years. One of the most widely-known marvels of such protection efforts is the Great Wall of China, a sight visited by more than 10 million travelers each year .
Historians agree that ~220 B.C. the first Emperor of a newly unified China, Qin Shi Huang, envisioned a grand plan to protect his kingdom from the invading Xiongnu nomadic horsemen of the north. Qin expanded the existing system of defensive walls along the northern border of China into one Great Wall in hopes this barrier would quell the barbarian attacks. Qin succeeded in creating a formidable defense structure, estimated to be 3,100 miles upon completion. The wall included watchtowers built at intervals, with a sophisticated warning and communication system of smoke signals, lanterns, and beacon fires.
Though the Great Wall slowed the attacks, this passive strategy was not enough to end the assaults of the fierce Xiongnu horsemen who often rode in groups of up to 300,000 archers. Roughly 100 years later, Emperor Wudi initiated an active campaign against the barbarians, to finally end their attacks. By sending out strong expeditions to disband the barbarian warrior groups at their sources, the Chinese finally established absolute rule for a period. This historical experience illustrates the need to supplement a passive protective strategy with an effort to actively engage a threat at its source.
In modern history, Israel embraced a similar method for protection by building a 100-mile line of defensive walls and trenches along the eastern side of the Suez Canal to protect Israelis from Egyptian artillery bombardment during the War of Attrition (1967-70). It was estimated that Israel invested $300 million in this massive defensive concrete and sand structure called the Bar Lev Line, reaching a height of 66-82 feet ....