In 968 an outstanding military commander, Dinh Bo Linh (924979), reunified the country after the collapse of the short-lived Ngo Dynasty (93967). He renamed the country Dai Co Viet, and moved the capital from Co Loa near Hanoi south to Hoa Lu to be farther from the Chinese threat. He also took the title Emperor Tien Hoang De (r. 968979), married five empresses simultaneously  the only Vietnamese king ever to do so  and built an elaborate palace and citadel. Like his more famous Chinese namesake, the ˉYellow Emperorˇ Qin Shi Huang, he not only unified the country, but employed extraordinarily cruel means to hold it together. In front of the citadel at Hoa Lu he is said to have kept a vat of boiling oil in which to immerse lesser offenders, while more serious criminals were fed to the palace tigers.