The world's longest reigning monarch was discharged three weeks later, but his illness served as a reminder to many of Thailand's 64 million people of the king's advancing years and increasing fragility.

The country laid on massive celebrations for his 80th birthday in December, just over a year after similar festivities to mark 60 years on the throne.

During his reign, Bhumibol has been a pillar of stability during often turbulent and bloody politics, including 18 military coups, the last of which was in September 2006 against Prime Minister Thaksin Shinawatra.

Despite limited constitutional powers, he wields enormous personal influence and has waded into politics on several occasions in favor of both democratic and military regimes.

Many Thais are worried for the future after his death as his heir apparent, 55-year-old Crown Prince Maha Vajiralongkorn, does not enjoy the wide respect accorded to this father.

(Reporting by Nopporn Wong-Anan, writing by Ed Cropley; Editing by Michael Battye)