On the 23d the 1st Marines extended to the eastern boundary of X Corps and relieved the Division Reconnaissance Company on Hill 884. That same day the enemy was treated to a novelty when 100 well aimed 16-inch projectiles, fired from a range of 40,000 yards, roared in like meteors on his positions in the area of Hill 951 (Map 20). Naval gunfire from the USS _New Jersey_ was being conducted by Marine spotters in forward OPs, who reported good coverage for the 2,000-pound rounds. Ammunition dumps and artillery pieces were destroyed while NKPA troops in the open suffered heavy personnel casualties, according to observers. Several more bombardments were contributed by the _New Jersey_ at the request of 1/1 and 3/1 during the balance of the month. Marine and attached Army artillery also gave excellent support with fire so accurate as to break up enemy counterattacks before they could be launched. Ammunition restrictions hampered the efforts of the 11th Marines (Colonel Custis Burton, Jr.) but the cannoneers never failed to respond to an emergency. The 90mm rifles of the 1st Tank Battalion (Lieutenant Colonel Holly H. Evans) continued to show good results with direct observed fire on enemy bunkers. Air support in September, concluded the Division report, was “generally inadequate and unsatisfactory.”[309] [309] _Ibid._ By the last week of September the Division right (east) flank was well protected, considering the rugged terrain. Not as much could be said for the other flank, northwest of the Punchbowl, where the sector of the Marines joined that of the 5th ROK Division. Since the Division sector was divided by high, roadless mountains, there was no rapid way of moving reserves other than by helicopter. In short, the 1st Marine Division was hard pressed to man a 22,800-yard MLR while keeping in reserve enough troops to help defend this sensitive area in an emergency. Plans were completed by General Thomas and the Division staff for the rapid displacement of a company from 2/1, the reserve battalion of the 1st Marines, to meet any such threat. Since a surprise attack was most likely to occur at night, it was decided that a helicopter lift of an element of the Division reserve should be made in the darkness of 27 September after a detailed daytime rehearsal.[310] [310] The remainder of this section is based upon the Type “C” Spec Rpt, “Employment of Assault Helicopters,” Part II, 1–9; HMR-161 and 1stShorePartyBn _HD_, Sep and Oct 51; _Cavalry of the Sky_, 165–167. In contrast to former Marine helicopters, which had no night-flying aids, the HRS-1 was equipped with few attitude of flight instruments. They were primitive compared to the sophisticated instrumentation of fixed-wing planes, and Lieutenant Colonel Herring sent his pilots on preliminary night indoctrination flights to memorize terrain features.