Earlier in the year the Marines had revised their estimate of enemy capabilities after the lengthening of the division MLR by I Corps and the subsequent heavy enemy attack. The re-evaluation placed the most likely course of Chinese action as defending their present positions with the 21 infantry battalions assigned and also cautioned that the Communists could mount a limited objective attack at any time of their choosing. Division intelligence estimated that the Chinese could muster up to “57 infantry battalions supported by 12 artillery battalions and 40 tanks and/or self-propelled guns” for a thrust into the Marine sector.[116] [116] 1stMarDiv ComdD, Apr 52, p. 1. The enemy, however, showed little disposition for any concerted ground attack during the remainder of April. But before the month ended, Marines, in conjunction with other I Corps divisions, had deluged the enemy with artillery and tank fire in Operation CLOBBER. The purpose of this shoot was to inflict maximum casualties and damage by employment of the element of tactical surprise. The reinforced 11th Marines, augmented for this occasion by Company D, 1st Tank Battalion and nine of the battalion’s 105mm howitzer and flame tanks, blasted Chinese CPs, bivouac areas, artillery and mortar positions, and observation posts. Marine frontline regiments joined in with their organic mortars. Since most of the firing took place at night when results were unobserved, no estimate could be made as to the effect of the operation on the enemy. A new Marine artillery tactic about this time was the counter-counterbattery program instituted by the 11th Marines. The regiment had developed this technique to counter superior enemy artillery strength. This situation, as well as the fact that I Corps artillery available to the division was considered inadequate for counterbattery support, led the Marine division to adopt the new program in May 1952. One provision required a battery in each battalion to select counter-counterbattery positions and occupy them for 24 consecutive hours each week. Another proviso of the program was the selection by each battalion of 10 roving gun positions that were to be occupied by a single weapon rotated to each place at least once weekly. By these tactics, the artillery regiment hoped not only to mislead the Chinese in their estimate of the strength and location of Marine artillery but also to dilute enemy counterbattery intelligence by causing him to fire into areas just vacated by friendly guns. “The effectiveness of the program was demonstrated on numerous occasions when the enemy fired counterbattery into unoccupied positions.”[117] An added advantage was that of providing deeper supporting fires on target areas.[118] [117] _PacFlt EvalRpt_ No. 5, p. 8-51. [118] LtCol Bruce F. Hillam comments on draft MS, dtd 31 Aug 66.