BANGKOK: Thai authorities on Saturday detained an activist attempting to mark the 1932 revolution that ended absolute monarchy, police said, a historical event that has become increasingly taboo under an ultra-royalist junta. The bloodless revolution on June 24, 1932 launched parliamentary democracy in Thailand. In recent years small groups of democracy activists have gathered each anniversary to lay flowers on a small bronze plaque marking the spot where revolutionaries proclaimed the end of absolute monarchy in a fiery speech lambasting the king. But the 30-inch plaque was mysteriously removed from Bangkok’s Royal Plaza this April and replaced with a new marker bearing a royalist message. On Saturday an activist, Ekachai Hongkangwan, was taken to a Bangkok military base for “attitude adjustment” after he tried to lay a replica of the original plaque on top of the new one, said Phanurat Lukboon, deputy Metropolitan Police commissioner. “He is now being held at the 11th army circle,” the officer told Agence France-Presse, referring to an army barracks.