It’s beginning to sink in now in Bangkok that the September 19 military coup which ousted Thaksin Shinawatra just a few months before elections was not really about corruption or democracy or rule of law. Nor was it, as some have claimed, a “different” (somehow more virtuous) coup.

As with US President George W. Bush and the Iraq invasion, slowly the justifications for the putsch are shedding away, showing that the military’s righteous claims of a determination to eliminate corruption and right the constitution are empty: when you have those motivations, you have ideas on how you will go about it.

Even those supposedly shrewd mass media opinion leaders who cheered any action to rid the nation of Thaksin – going so far as to generously print by the score baseless rumors – are now finding fault in their white knights.

The coup was about Thaksin’s ambition and misrule, certainly, but what really got General Sonthi Boonyaratklin and his cohorts to move was the issue of succession to the throne. There was a clear meeting of minds between the crown and the military, through King Bhumibol Adulyadej’s number one aide Prem Tinsulanonda, that they did not want Thaksin in a position to exert influence on the passing of the Chakri Dynasty mantle to Crown Prince Vajiralongkorn.

Theoretically the mechanism for the handover when King Bhumibol, nearly 79, passes away, is clear and simple. By a long tradition of primogeniture, by the 1924 Palace Law of Succession and by the pattern established in the pile of constitutions crafted, eliminated in army coups and crafted again over six decades, the crown should go in the first place to a son of the king – and Prince Vajiralongkorn is his only son.

In the absence of a son -- and ‘absence’ can give way to multiple interpretations -- it can go to a daughter of the king. Recent constitutions have also allowed that the king can both make his own decision whatever the law, and he can also unilaterally change the 1924 law, with the approval of the privy council. (The post-coup interim constitution doesn’t address succession, leaving it, ironically, to “constitutional practice”.)

But the Thai monarchy is no different from other monarchies in history: in human hands in a secretive palace and government, all these principles give way to power politics.

The first reality of succession is that it will be in the hands of the king’s Privy Council. They are empowered to implement the orders the king leaves behind or carry out the succession on legal principles if the king hasn’t given instructions.

In fact, there will be no way of knowing whether the privy council does act in this way or makes its own decisions. The legislature will have to sign off on it though, so whatever decisions is made must be firm, convincing and acceptable.

The second reality of succession is that the military has to agree. As they showed again in September, for the 11th time in 60 years, they can decide who runs the country. And so who controls the military can have a big impact on succession.

The third reality is that Prince Vajiralongkorn is widely disliked and feared, while his sister is very popular. That might not matter, since royal sovereigns are not elected. But in the 1980s Princess Sirindhorn was given tenure as a history lecturer in the Chulachomklao Military Academy, the training ground for Thailand’s brass, and by now an entire generation of officers has passed through her classes. The bonding that has taken place is well known.

By comparison, the prince, himself a military officer by substantial training, has not developed such relationships. Very possibly, the Thai military leadership is biased in favor of the princess, though with significant elements who for various reasons ally themselves with the prince.

These factors in succession began to come into focus when Thaksin began spending money in the 1990s on the royal family, to the point, as he allegedly boasted in private, that he had at least some of them in his pocket. But they became strikingly clear to the palace and its allies when Thaksin began putting his own men in the top command positions of the military. Amid all the political infighting last year and early this year, the key indicators of what was going on were Thaksin’s fight with coup leader General Sonthi on staffing key positions, a battle Thaksin lost – ensuring the coup was successful.

The palace has long used its own proxy generals to maintain sway on the military, and that has been the key role of Privy Council head, General Prem Tinsulanonda, since he was King Bhumibol’s hand-picked prime minister in 1980. His first duty on the privy council is to keep the military locked in step with the palace. To that end Prem has recruited a number of his own loyal followers from the military and civilian bureaucracies to back him up on the council. Unsurprisingly, one, General Surayuth Chulanont, was made prime minister after the coup.

With a Thaksin-cleansing operation still going on in the military and bureaucracy, the effect is to make sure the army and the political leadership are lined up behind the privy council and do not pose a threat to whatever Prem and his fellow king’s councilors do when King Bhumibol passes.

That doesn’t guarantee everything, given the possible divisions between pro-prince and pro-princess factions, or even the potential for a “monarchist” uprising like that of the past year to make demands on the process. That means that it is ultimately up to Princess Sirindhorn to send the right signals if tensions arise at any level.

All that makes this coup no different from nine of the 11 successful putsches of Bhumibol’s reign. Aside from the 1951 and 1977 coups – they were against royal power – these coups have always been about ensuring the solidarity and strength of the royal-military alliance in the face of potential challenges, be they pro-democracy students, communist insurgency, or a headstrong elected prime minister.

In each as, as this time around, the coup leaders showed no real agenda for sorting out national economic or social problems, no sense of what they wanted the constitution to achieve, no guidance for Thai society going into the future. But in the absence of any such agenda, they point directly to what it was all about.