result in a breakthrough, such as the 4th Panzer Army suffered during Operation Winter Storm or the British 1st Armored Division suffered at Campoleone. That is referred to as a failed breakout. A breakout may be attempted in conjunction with relief, which may be essential especially if the invested force has already experienced failed breakout attempts (again, as in Winter Storm). First World War As the situation on the Western Front during the First World War has been widely regarded as a single continent-long siege, rather than a series of distinct battles, it is possible to consider offensive action from the Allies as a type of breakout. In that sense, the Allied armies may be considered encircled, albeit on a hitherto-unheard of scale, with the German army to their east, the Alps and the Pyrenees to their south, and the sea to their west and north. Indeed, as the Dunkirk evacuation illustrated, despite having by far the largest navy in the world, those armies' amphibious movements were nearly impossible logistically. Similarly, as is seen at the Battle of Sarikamish, mountainous terrain remained a significant obstacle to military movement and could inflict numerous casualties. Strategy and tactics The classic breakout strategy involves the concentration of force at one weak point of the encircling force. In the case of the Battle for North Africa, a variation of the tactic was used by German Field Marshall Erwin Rommel, who secured both his flanks before quickly penetrating into the enemy's rear. During the Second World War, British General Bernard Montgomery also adopted the strategy by attacking the enemy's narrow front. Breakout maneuvers, despite their own myriad risks, may become necessary by a number of disadvantages encircled forces suffer: They are vulnerable to concentrated artillery fire. They are vulnerable to use of weapons of mass destruction. They, at some point, exhaust their supplies if resupply is not possible by air. They cannot evacuate the dead and the wounded. They are vulnerable to loss of morale and discipline. The invested force suffers from the disadvantages resulting from occupying a confined space and also from those resulting from a lack of resupply. Therefore, the encircling force has a significant tactical advantage and the advantage of time. It may, in fact, choose to not engage their enemy at all and simply wait it out, leading to eventual exhaustion of ammunition if the invested force gives battle or to