Understanding War by Trevor Dupuy’
To some modern military thinkers this is a truism needing no explanation or justification. Others have asserted that prepared defenses are attractive traps to be avoided at all costs. Such assertions, however, either ignore or misread historical examples. History is so fickle that it is dangerous for historians to use such words as “always” or “never.” Nevertheless I offer a bold counter-assertion: never in history has a defense been weakened by the availability of fortifications; defensive works always enhance combat strength. At the very least, fortifications will delay an attacker and add to his casualties; at best, fortifications will enable the defender to defeat the attacker.
Anyone who suggests that breakthroughs of defensive positions in recent history demonstrate the bankruptcy of defensive posture and/or fortifications is seriously deceiving himself and is misinterpreting modern history. One can cite as historical examples the overcoming of the Maginot Line, the Mannerheim Line, the Siegfried Line, and the Bar Lev Line, and from these examples conclude that these fortifications failed. Such a conclusion is absolutely wrong. It is true that all of these fortifications were overcome, but only because a powerful enemy was willing to make a massive and costly effort. (Of course, the Maginot Line was not attacked frontally in 1940; the Germans were so impressed by its defensive strength that they bypassed it, and were threatening its rear when France surrendered.) All of these fortifications afforded time for the defenders to make new dispositions, to bring up reserves, or to mobilize. All were intended to obstruct, to permit the defenders to punish the attackers and, above all to delay; all were successful in these respects. The Bar Lev Line, furthermore, saved Israel from disastrous defeat, and became the base for a successful offensive.