Battle for the Punchbowl: The U. S. 1st Marine Division 1951 Fall Offensive of the Korean War Page: 310

(6) Reports have been received that North Korean troops carry wooden clappers
for deception purposes to simulate gun fire and at the same time preserve
ammunition.
(7) Local civilians are employed to spy on the enemy and obtain information
concerning the terrain over which the attack will take place.22
There were other elements characteristic of an NKPA attack:
The enemy deployed in depth and employed numerous waves of troops
depending on the formation of the United Nations defensive positions. As a rule,
too much strength was not concentrated in the spearhead of the attack. The
terrain determined the number of men used. If the leading element failed to break
through United Nations lines, a second and third wave were used until a
breakthrough was established ... .23
The UN forces, the Marines among them, adopted "defense perimeters in depth,
with physical contact between units and prearranged fields of fire." These "prevented
enemy patrols from determining friendly boundaries." Also, "rigid control of fire...
denied the enemy this information. Only troops immediately to the front of the enemy's
probing action fired on him. Friendly flank elements held fire except in the face of a
sizeable enemy attack." Another report described the UN preventive measure similarly
as "a tight perimeter in depth, together with coordination of fire between units, permitted
the United Nations units to withstand and repel enemy counterattacks."24
The enemy's defensive layout, too, followed his doctrine. NKPA defensive lines
followed this basic structure. An "outpost line" of defense was "located 6 to 8 miles in
front of the main line of resistance. . . and is designed to harass and delay the hostile
attack. Comprised of hasty positions manned by forward detachments, this defensive
belt allegedly may be omitted entirely at the discretion of the senior commander." Either
22 U. S. IX Corps, "Enemy Tactics, Techniques, and Doctrine," 20-21.
23 Headquarters EUSAK, "Enemy Tactics," 39.
24 Headquarters Far East Command, "North Korean Defensive Tactics," 32; Headquarters EUSAK,
"Enemy Tactics," 84.

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