On 11 August, General Walker verbally instructed Brig. Gen. Garrison H. Davidson, an Engineer officer, to lay out this secondary defense line. Davidson, after looking over the ground, recommended to General Walker that because of better defensive terrain the line should be somewhat farther back toward Pusan than General MacArthur had indicated. General Walker replied that the line would be constructed where General MacArthur had indicated it should go.
General Davidson began laying out the line with very few resources. He received some help from Brig. Gen. Crump Garvin and the 2nd Logistical Command at Pusan and from the 2nd and 25th Divisions. This line, known as the Davidson Line, began on the east coast at Sodong-ni, approximately eight miles north of Ulsan, and extended generally west along high ground to a point northeast of Miryang, then curved down the ridge east of Muan-ni, turned south across the Naktong River and anchored on the high ground northeast of Masan. General Walker would not approve Davidson's recommendation to remove all houses from in front of the line to clear a field of fire. Davidson succeeded in laying a trace of the line on the ground, cleared fields of fire except for houses, ordered material for fortifications, and was able to have a few positions dug before he reported to the 24th Division as assistant division commander on the first of September. [21-46 ]