Nguyen Phu Trong: Vietnam’s long-serving leader dies at 80

At the same time, he fervently clung on to his socialist ideals. “He was a career lifelong ideologue… he was a true believer, and I think that’s why in some ways relations between Vietnam and China have grown so close,” said Zachary M Abuza, a professor and Southeast Asia expert with the National War College in Washington DC.

“He always believed in making the party clean and relevant so that the party could live with the country for another 1,000 years – that’s his quote. So he saw the fate of the Vietnamese Communist party and the nation as bound together,” said Giang Nguyen, a visiting senior fellow with the Institute of Southeast Asian Studies in Singapore and former BBC Vietnamese editor.

Mr Trong launched his “blazing furnaces” campaign to root out corruption that deepened in tandem with Vietnam’s growth. Close to 200,000 officials are estimated to have been criminally charged or to have faced disciplinary action since then.

But there are few signs it has truly succeeded in stamping out the problem. The country still performs dismally, external in international corruption rankings. In recent months Vietnam has been rocked by one of its biggest fraud scandals ever, involving a staggering $44bn (£34bn) filched from banks.

The anti-corruption drive has been seen as sparking a critical shortage, external in the public service sector. It’s also been seen as contributing to instability within the Communist Party, where so many top officials have been purged – due to corruption or infighting – that very few are left as possible successors, particularly in the paramount political leadership team, the Politburo. Only two currently meet the conditions to inherit his post: Mr Lam and Prime Minister Pham Minh Chinh.

“The talent pool hasn’t been prepared by Mr Trong. It shows he couldn’t control the forces within the party anymore,” said Mr Nguyen.

Dr Abuza pointed out that the anti-corruption drive in many ways “served to delegitimise the party in ways that [Trong] didn’t expect, because it exposed just how sweeping corruption is at the highest level of the party”.

During his rule Vietnam also continued to tighten its control on human rights and freedom of speech. It has jailed or deported scores of dissidents, activists and bloggers, and passed draconian laws limiting the press and internet.

His death, and the question of succession that it poses, puts Vietnam in uncharted waters. For many Vietnamese, “we share the feeling of anxiety of the unknown”, said Mr Nguyen.

“It is the end of an era. That version of communism or socialism, the old times, it’s now gone. What’s next is going to be very difficult to foresee. The system is still there, but without that veneer of ideology and ideals.”

Additional reporting by BBC Vietnamese.