King Bhumibol Adulyadej, who died peacefully on Thursday, was the world’s longest-reigning monarch, credited with restoring the influence of Thailand’s royalty during 70 years on the throne and earning the devotion of many of his subjects.

The Royal Palace said Bhumibol died “in a peaceful state” at Siriraj Hospital in Bangkok, where he had been treated for various health problems for most of the past decade.

Bhumibol ascended to the throne in 1946, when his brother, 20-year-old King Ananda Mahidol, was found dead of a gunshot wound to the head in a palace bedroom under circumstances that remain mysterious. Bhumibol, then an 18-year-old prince, was named king 12 hours later following an extraordinary legislative session.

With the king’s passing, the world’s longest reigning monarch is Queen Elizabeth II, who ascended to the British throne in 1952.