Horii linked up with the advance party at Kokoda and began to assemble his force for the overland advance. By 26 August, it consisted of the 144th Infantry Regiment (three battalions), the 41st Infantry Regiment (2nd and 3rd Battalions, with the 1st Battalion yet to arrive—joining the main force on 14 September) and 1st Battalion, 55th Mountain Artillery Regiment. The 3rd Battalion was tasked with protecting the force's line-of-communication. The 41st Infantry Regiment fielded only 1,900 troops since both the 1st and 3rd Battalions had approximately 400 detached from each for road construction and supply tasks. The force has been estimated at 6,000. Horii commenced his advance with each man carrying sixteen days' rations. Troops of both regiments were seasoned veterans. The 41st Infantry Regiment had fought against Australians in Malaya.