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
Ancient maritime history Ancient maritime history Maritime history dates back thousands of years. In ancient maritime history, evidence of maritime trade between civilizations dates back at least two millennia. The first prehistoric boats are presumed to have been dugout canoes which were developed independently by various stone age populations. In ancient history, various vessels were used for coastal fishing and travel. A mesolithic boatyard has been found from the Isle of Wight in Britain The Arabian Sea has been an important marine trade route since the era of the "coastal sailing vessels" from possibly as early as the 3rd millennium BC, certainly the