At Vann's insistence, a personnel shake-up took place in III Corps when President Thieu replaced Du with Major General Nguyễn Văn Toàn, whose outwardly confident and assertive nature was the complete opposite of Du's. The actions at Kon Tum for the following two weeks became characterized by massed PAVN assaults that were lashed by B-52, tactical air, and helicopter gunship attacks. ARVN troops then counterattacked over the remains of the attacking wave. On 26 May, four North Vietnamese regiments supported by armored forces managed to punch a hole in the defense, but their advance was halted by U.S. helicopters firing the new TOW missiles. During the following three days of fighting, 24 North Vietnamese T-54 tanks were destroyed by TOWs and the breach was sealed.