[338] The 1st Commonwealth Division, to the Marine right, utilized a different defense system. Instead of relying on the COPs forward of the main line of defense as major deterrent positions, the British preferred to include all strategic terrain features within the MLR itself. They followed a policy of active patrolling to the front and, at night, occupied selected ground sites, preferring to fight the enemy from their main battle positions rather than from more isolated COP positions. _PactFlt EvalRpt_ No. 6, Chap. 9, pp. 9-92, 9-93. [339] The military crest is that point along the slope of a hill from which maximum observation up and down the hill can be obtained. The topographical crest is the highest point on a hill or ridge. [Illustration: MAP DIAGRAM 20 K. White ORGANIZATION OF GROUND DEFENSE WINTER 1952–1953] Altered defense concepts, beginning in October, took the following form: (1) The trace of defensive positions followed the topographical crest (A) rather than military crest (B) of key terrain features. (Map diagrams 20 and 21 illustrate these changes.) (2) Fighting positions and emplacements were dug a short distance downslope (C) from the topographical crest. (3) Trenches on the topographical crest permitted easier, faster, and more protected access to fighting positions from the reverse slope and support area (D). (4) Positions on the topographical crest were less vulnerable to enemy artillery because it was more difficult for the enemy to adjust his fire on these positions than on trenches dug along the military crest. Many shells simply passed over the top (E) of the hill. (5) Certain hills and noses were selected and organized so that trenches and gun emplacements, encircling the crest, would form mutually supporting positions (X). (6) Machine guns were moved from the draws (Y) to hilltops and noses (Z) where better long-range observation and fields of fire existed. [Illustration: MAP DIAGRAM 21 K. WHITE TYPICAL HILL DEFENSE (Cross Section) WINTER 1952–1953] Another change in the improvement of field fortifications came into use during the winter months. A different type of barbed wire obstacle, called “Canadian,” “random,” or “double-apron” wire, began to find favor with Marine infantrymen. Canadian wire consisted of two parallel rows of three-strand barbed wire fencing, erected about three feet apart. The void was filled in with additional barbed wire, placed at random, but connected to the parallel fences.[340] The new type barbed wire appeared more effective for several reasons. Besides being simple and fast to emplace, Canadian wire merely became more entangled by artillery shelling, which quickly ripped apart the standard double-apron barbed wire previously used in COP slope defenses.