Bullard reports orders to Horii of 28 August, " advance to the southern slopes of the Owen Stanley Range ... but amass your main strength on the north side of the range in preparation for future operations". Bullard notes a degree of ambiguity with respect to defining the "southern slopes". On 8 September, the 17th Army ordered Horii to assemble the 41st Regiment in the Kokoda area. Horii did draw back the main body of his force but continued to thrust forward. When, on 19 September, Hyakutake became aware that Ioribaiwa had been occupied on 16 September, he "issued strict orders for front-line troops to immediately occupy a position to the north of Mawai". An order of 23 September was to secure the Isurava–Kokoda area as "a base for future operations". Horii had out-run his supply line and therefore his force was faced with extreme rationing and was unable to advance any further. On 24 September, the 2nd/144th Battalion withdrew from Ioribaiwa. The 3rd/144th Battalion formed the rearguard and withdrew during the night of 26 September.