A sudden encirclement of a modern army is a cataclysmic event, comparable in its ay to an earthquake or other natural disaster. On the map it often takes on a surgically precise appearance. On the battlefield it is a rending, tearing operation that leaves the victim to struggle in a state of shock with the least favourable military situation: his lines of communications cut, headquarters separated from troops, support elements shattered, and front open to attack from all directions. The moment the ring closes every single individual in the pocket is a prisoner.
Death is in front of him and behind him; home is distant dream. Fear and panic hang in the air. Escape Is the first thought in the minds of commanders and men alike, but escape is no simple matter. With the enemy on all sides, with rivers to cross, turning around an army that numbers in the hundreds of thousands with all its men, weapons, vehicles, supplies, and equipment and marching it 10, 20, 30, or more miles is a cumbersome and perilous undertaking.
The first effect of the impending encirclement is vastly to intensify the normal confusion of battle because the attack is carried into areas most difficult to defend and because as the advance continues the victim progressively loses the points of reference, the means, and the ability to orient himself for a coherent response.
Earl F Ziemke: Stalingrad to Berlin – The German Defeat in the East, Center of Military History, US Army, Washington DC, (1968), Page 55