Khosrau II of Persia

Khosrau II (Khosrow II, Chosroes II, or Xosrov II in classical sources, sometimes called Parviz, "The Ever Victorious" – (Persian: خسرو پرویز), was the twenty-second Sassanid King of Persia, reigning from 590 to 628. He was the son of Hormizd IV (reigned 579–590) and the grandson of Khosrau I (reigned 531–579).

Khosrau II in "The Banner of Kaviyan"
With the help of the Banner of Kaviyan, the army of the King of Kings Khusro, led by marshall Shahr Baraz succeeded in reconquering Palestine, Egypt and Asia Minor and dreamed of sacking Constantinople. With these victories, Khusro considered the Banner of Kaviyan to be a treasure too valuable to risk in battle. He therefore had it sent to Ctesiphon for safe-keeping. It was hidden away in the Imperial Palace with only a few trusted officials knowing where in the elaborate structure it was placed. This was to prevent rebellion as possession of the banner would leave the rebel army invincible.

But without the banner, the Persian victories were reversed and the Romans went on the offensive. Khusro feared to enter Ctesiphon since it was prophesized that he would be destroyed if he did and so fought on without the banner. However, he continued to lose ground and so eventually went to Ctesiphon to retrieve the banner. But none of the officials who knew where it was hidden remained and after desperate searching it was not found. Khusro was forced to flee but was eventually captured by his son and killed by slow torture.