The coup of 716

In 716 Kapgan Khan beat the Bayirku on the Tola and rode home without keeping his order.^[1] A straggler from the beaten army was waiting in a willow wood. He beheaded the khan of the Second Khaganate there.^[1] The head went to Chang’an.^[1]

The killing at the court

Kapgan had ruled for twenty-four years. He had set his own son on the second throne as Lesser Khan.^[1] The succession he had built lasted a few days.

Kül Tegin killed the Lesser Khan, Kapgan’s brothers and his sons, and the men of his court. He set his own elder brother on the throne as Bilge Khan.^[1] Tonyukuk had served Kapgan and been pushed aside by him. He was spared.^[1] Historians argue whether he stood behind the killing or survived it because his daughter was married to the new khan. The sources cannot settle the question. The two men who could have said speak only in their own inscriptions.

The inscriptions on the accession

The Kül Tegin inscription and the Tonyukuk inscription were both raised by the winners of 716. Neither gives an account of the night.^[2] They describe the restoration of the state, the campaigns and the loyalty owed to the khan. They pass over the accession in silence, and that silence is itself a statement.

Bilge Khan does say that the people had turned against their khans and that he took the throne over an exhausted realm. The succession is presented as a rescue, not as a coup.^[2]

Consequences

The killing ended the line of Kapgan. It gave the khaganate the three men who ran it for the next twenty years: Bilge on the throne, Kül Tegin at the head of the army, Tonyukuk in council. This is the arrangement the great inscriptions were raised to commemorate, and it was the last stable period the Göktürk state had.

It also shows a pattern. Twice in thirty years the succession of the Second Khaganate was settled by killing the previous khan’s household. The khaganate did not survive the third time it was tried, in 741.