U.S. and Army of the Republic of Vietnam (ARVN) forces had not threatened the PAVN/VC in the area since Operation Junction City concluded in May 1967, but with the rainy season coming to an end the 1st and 3rd Brigades of the 25th Infantry Division reinforced by a tank battalion and an air cavalry squadron would take advantage of the improved weather to sweep the area and help build two new Special Forces camps.

[1] Operation Yellowstone commenced on 8 December with two infantry battalions from the 1st Brigade landing by helicopter unopposed at the hamlet of Katum on Highway 4.

When the two battalions finished securing the area, a task force consisting of tanks, artillery and engineers moved along Highway 4 from Tây Ninh Combat Base and began building Firebase Custer (11°39′47″N 106°13′19″E / 11.663°N 106.222°E / 11.663; 106.222), which would serve as the 1st Brigade’s forward base and Firebase Beauregard (11°37′34″N 106°15′58″E / 11.626°N 106.266°E / 11.626; 106.266) 5 km southeast on Route 246 near the village of Bo Tuc.

[1]: 29 On the evening of 31 December while a 24-hour New Year's truce was in effect, the 271st and the 272nd Regiments of the PAVN 9th Division moved into attack positions around Firebase Burt.

[1]: 30 [2] This article incorporates public domain material from websites or documents of the United States Army Center of Military History.