() guarding the eastern approach to Hiệp Đức. The 51st was able to advance only part way up Hill 1460 and could not dislodge the PAVN infantry holding the crest. Meanwhile, elements of the 3rd Division's 2nd Regiment were across the Quế Sơn Valley and had seized the hill above Chau Son, thus controlling Route 534 into Hiệp Đức. On 24 January, the 3rd Division's attack continued, the objective was the former Firebase O'Connor () on high ground just east of Hiệp Đức. On 26 January, with the ceasefire imminent and VC forces moving into the populated lowlands of Quảng Nam, the 3rd Division had to terminate its attack. A strong counterattack by the 711th Division forces still on Firebase West prevented the 3d Division's infantry from gaining Firebase O'Connor, but the heavy casualties sustained by the 71lth demoralized and weakened it severely. By the end of January, 3rd Division troops were busy clearing VC forces from the hamlets west and southwest of Da Nang, and by the end of the month only one hamlet remained under PAVN/VC influence in Đại Lộc District. In Quảng Ngai Province between 23 and 26 January VC forces infiltrated into assembly areas in the lowlands and on 27 January attacked throughout the lowlands, rocketing the provincial and district capitals, interdicting Highway 1 and overrunning several Regional Force and Popular Force outposts. In southern Quảng Ngai, the PAVN 52nd Regiment, 2nd Division, established defenses around the district town of Ba Tơ, which it had controlled since the fall of 1972. Rather than challenge this position, the ARVN deployed to prevent the 52nd Regiment from moving toward the lowlands. Holding its 1st Regiment in reserve, the PAVN 2nd Division used one battalion to support VC forces in Mộ Đức District, kept one battalion in the base area, and deployed the third to support the attack of the 141st Regiment in Duc Tho District. On 27 January the 141st Regiment, supported by two battalions of the PAVN 12th Regiment, 3rd Division reached Highway 1 south of Duc Tho and secured the rest of the district south to the border of Bình Định Province, including Sa Huỳnh Base, in which two battalions of the PAVN 12th Regiment, 3rd Division, supported the attack of the 2nd Division. Since the PAVN had blocked the only north - south line of communication and had secured a seaport, however small and undeveloped,