Korean youths, posing as fishermen, brought intelligence which Clark included in his daily radio messages. One of these spies made an effort to count the guns on Wolmi-do and describe the locations. Others took measurements of the Inchon sea wall and penetrated as far inland as Seoul to report numbers and positions of NKPA troops. Clark declined all offers to evacuate him. As the climax of his exploit, he managed to restore the usefulness of the lighthouse on Palmi Island which the enemy had put out of commission. This structure, the former entrance beacon for Inchon by way of Flying Fish channel, served him as a refuge when he had to leave Yonghung-do hurriedly just ahead of NKPA troops who landed in force and butchered 50 civilians of both sexes. Clark, who received a Silver Star, stuck it out on Palmi until midnight of 14 September, when he turned on the beacon light to guide the amphibious task force. _The Landing Force Plan_ The decisions behind the Landing Force Plan--1st Marine Division OpnO 2-50--obviously had to be made without benefit of Lieutenant Clark’s reports, since the publication date was 4 September 1950.[96] It is to the credit of these conclusions, therefore, that so few of them had to be corrected in the light of first-hand evidence from the objective area. [96] See Appendix G for a chronological list of all 1st Marine Division operation orders during the Inchon-Seoul operation. Although CG X Corps was the assigned Expeditionary Troops Commander, planning on the Corps level was concerned almost entirely with the exploitation phase following the seizure of the beachhead. All Landing Force planning was done on the _Mount McKinley_ by the Division in close coordination with PhibGru One. The first consideration, as viewed by the Navy planners, was that the tides, currents, and tortuous channels of Inchon made necessary a four-hour daylight approach to the transport area. This meant that 1130, at low tide, was the earliest hour of arrival; and not until about 1700 would the next high tide provide enough water for an assault landing. On 15 September a maximum high tide of 31 feet could be expected at 1919. Evening twilight came at 1909. It was estimated initially that 23 feet of water would take the LCVPs and LVTs over the mud flats, but that 29 feet were necessary for the beaching of the LSTs. In view of these conditions, PhibGru One planners concluded that 1700 was the best time for landing the LCVPs and LVTs, and it was decided to beach the LSTs at about 1900. Simultaneous landings of troops on Wolmi-do and the mainland were contemplated.