“There are decades where nothing happens, and there are weeks where decades happen,” Vladimir Ilych Lenin famously said. Sometimes decades get condensed into one single day, which changes dramatically the political dynamics of a country. February 8 was one of those days for Thailand.

It was supposed to be a regular Friday, no different from any other, except for the scheduled deadline for political parties to announce their premiership candidates ahead of the March 24 elections. That day, everyone expected that General Prayuth Chan-ocha, who took power in a coup in 2014, would announce his candidacy. His election seemed very much guaranteed, given the new constitution promulgated by his government in 2017, which gives the army complete control over the senate and almost a final say over the appointment of prime minister. Yet something much bigger was in the making.

In the early morning, the Thai Raksa Chart Party, a newly created political organisation linked to the overthrown Prime Ministers (and siblings) Yingluck and Thaksin Shinawatra, made an announcement that shook the whole country. It declared Princess Ubolratana Rajakanya Sirivadhana Varnavadi, King Maha Vajiralongkorn’s elder sister, as its prime ministerial candidate. Ubolratana, a famous actress and trendsetter in Thailand, had officially relinquished her royal titles in 1972, when she married an American man and decided to live in the United States.

After divorcing him in 1998, Ubolratana moved back to Thailand in 2001 and has since won public acclaim through acting and charitable work, while being rumoured to be on friendly terms with Thaksin Shinawatra, who was deposed by a military coup in 2006 but has remained heavily involved in Thai politics.

The news seemed to crack Prayuth’s plan to put a democratic stamp on his leadership and signal a tectonic shift in the country’s political alliances. This was the first time in Thai history that a member of the royal family ran for office. Ubolratana’s candidacy, everybody assumed, was going to be a home run, especially given how difficult it was going to be for anyone to campaign against a candidate who cannot be legally criticised. According to the existing lese-majeste law, anyone who criticises a member of the royal family could be handed between three and 15 years in prison.

Even more importantly, her name on the ballot was going to divide conservative and pro-monarchy forces pushing them to choose between supporting the princess herself or the military general. The announcement seemed to signal a deal being brokered between the Shinawatras and the palace, after decades of rivalry which had caused much political turmoil in the country.

As soon as the announcement was made, two questions emerged: should Ubolratana be considered a member of the royal family and would Prayuth dare to go head to head with her on a public forum? Over the course of the day, both questions were answered.

Later that morning, General Prayuth accepted his nomination by the pro-army Palang Pracharat Party. “Although I served as a soldier for all my life, I am [still] willing to sacrifice myself in order to protect Thailand,” Prayuth said. The general who had built his reputation around his claim to be the protector of the monarchy was now going to compete in an electoral race against a member of the royal family.

Right after Prayuth’s declaration, his party filed an objection to the princess’s candidacy with the Election Commission, arguing that her party had broken constitutional rules prohibiting the use of the monarchy for political purposes. This position was echoed in the public where a number of ultra-royalists voiced their discontent with the princess’s actions while pro-Shinawatra activists, who have historically criticised the use of the lese-majeste law, threatened to report them for violating that same law.

In the evening, some 13 hours after Ubolratana had announced her candidacy, her younger brother – King Vajiralongkorn – issued a royal statement, which answered the questions at hand and provided another plot twist to the longest day in Thai history.

“Despite the fact that Princess Ubolratana relinquished her titles – in compliance with the Palace Laws – she has been maintaining her status as a member of the Chakri royal family,” the king’s statement read. “Any attempt to involve high-ranking members of the royal family in the political process – by whatever means – would be a breach of time-honoured royal traditions, customs and national culture. Such actions must be deemed a transgression and a highly inappropriate act.”

This effectively put an end to Ubolratana’s daylong political career.

To an outside observer, February 8 may look like much ado about nothing. After all, by the end of the day, the electoral race looked exactly as it had 24 hours earlier, with Prayuth still running virtually unopposed, thanks to the support of a senate that his military government had hand-picked. Yet this daylong electoral earthquake left behind major fault lines in Thailand’s political landscape.

The princess’s short-lived candidacy revealed a rift within Bangkok conservative elites, some of whom showed that their hate for the Shinawatras may be even stronger than their adulation for the royal family. It is no secret that many of the most powerful families in Thailand have had a rocky relationship with the new king but their unprecedented vocal condemnation of the princess’s decision to run for office suggests that their alliances with the palace may not be as unwavering as previously assumed.

At the same time, the relation between General Prayuth and King Vajiralongkorn seemed also to have been affected. There have been unconfirmed reports that on February 10, the king summoned the highest military ranking officers to his house in Munich, where he continues to spend most of his time even after taking up the throne.

Some observers speculated that the fate of the upcoming elections, the reaction to the princess’s candidacy, and the possibility of another military takeover would be discussed at the meeting. Whether that was the case or not, allegedly no invitation was extended to the ruling general, suggesting that the king is increasingly putting his trust in other factions of the Thai army.

Finally, the events of February 8 also exposed a division within the so-called pro-democracy camp between those who celebrated the nomination of the princess as a brilliant tactical move and those who saw it as a huge mistake, which could have made monarchic control over the country stronger and further postpone a return to democracy. To be sure, such disagreements are not new among progressive forces, but the furious arguments that ensued between the two camps suggest that the unified popular support for forces linked to the Shinawatras may also be frailer than expected.

Historically, the Thai army has used similar moments of a division to legitimise military coups. Rumours of an impending countercoup against the government of General Prayuth are already circulating. This is indeed one of the most peculiar features of Thailand, a country in which the army can orchestrate a coup against an existing military rule.

Whether these events will be the prelude to another military takeover or a highly militarised election or not, what is definitely clear is that that five years of military rule have not achieved any of its declared objectives – to resolve political tensions and pacify the country.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial stance.