sentences:  The 258th Marine Brigade, with two battalions, was also near Phú Lộc, while the 914th RF Group of three battalions guarded the Hải Vân Pass.On the morning of 21 March the lead battalions of the PAVN 324B and 325th Divisions, together with the independent Tri-Thien Regiment, with heavy artillery support, assaulted South Vietnamese positions from the Bo Corridor to Phú Lộc.The attacks against the Marines in the Bo Valley were repulsed with heavy PAVN losses, but the Phú Lộc sector, taking the brunt of the attack, began to crumble.