Only two days had been available for training and rehearsals, but not a minute was wasted. All morning on the 13th the embarkation point section separated the supplies into balanced loads of about 800 pounds per helicopter. Loading commenced at 1520. Half an hour later, seven aircraft were ready to depart while four others went ahead to carry the landing point section to the previously reconnoitered site. The route followed the valleys as much as possible, so that the helicopters were in defilade most of the way. Smoke was laid down by the 11th Marines for concealment. The landing point section managed in 20 minutes to clear an area of 20 × 40 feet (later enlarged to 100 × 100 feet) and mark it with fluorescent panels. At 1610 the first HRS-1 hovered with cargo nets suspended from a hook released by manual control. A few minutes later it took off with five walking wounded and two litter cases. Each helicopter carried out as many casualties as possible, depending on the amount of gasoline in the fuel tanks. Only 30 minutes passed from the time one Marine was wounded and the time of his arrival at a hospital clearing station 17 miles behind the firing line. Radio provided communications between helicopters in flight, HMR-161 headquarters, 2/1 CP, and the Shore Party team at the landing site. Fifteen aircraft were employed for one hour, three for two hours, and one for two hours and 45 minutes--a total of 28 flights in over-all time of 2½ hours. The helicopters landed at intervals of two minutes and took off as soon as the landing point section could put the casualties aboard. And though an altitude of 2,100 feet restricted loads, 18,848 pounds of cargo had been lifted into the area and 74 casualties evacuated when the last “chopper” returned to X-83 at 1840. To even the most pessimistic observer Operation WINDMILL I was a complete success, so successful that a similar operation, WINDMILL II was conducted on the 19th. Two days later the first helicopter lift of combat troops was completed. A new era of military transport had dawned. _The Fight for Hill 749_ Although 2/1 alone had 240 Korean cargadores attached, the 7½ tons of helicopter-borne supplies, largely ammunition, were vitally needed by the two assault battalions of the 1st Marines. After relieving Fox Company of 2/7 south of Hill 749 at 1100 on the 13th, Lieutenant Colonel Nihart’s 2/1 jumped off to the attack an hour later. Stiff opposition was encountered from the beginning. The relief of the remaining two companies of 2/7 was complicated by the fact that they were some 400 yards from the position reported, on the reverse slope of Hill 749. Throughout the day these Marines were heavily engaged with the enemy.[286] [286] Sources for this section are the same as for the previous section except when otherwise noted.