The protesters’ actions were coordinated via Facebook, Twitter and Telegram. The mob was moving in a column formation, the head of which reached the Foreign Ministry building that is halfway to the Government House.
The protesters, which closed the rear, only left the Monument Square, when the column stretched for more than 1.5 kilometres (0.9 miles).
The mob demanded that the powers of the king be curbed and called on Thailand's Prime Minister Prayut Chan-o-cha, who came to power after a coup in 2014, to resign.
The protesters chanted slogans, such as "Down with Prayut," "Away with feudalism, hail to the people!" and "Out with the dictatorship, long live democracy!"
The police blocked traffic near the foreign ministry building and constructed road barriers, but are expected to not prevent the protesters from moving further and instead ensure order. Meanwhile, security forces began to set up a barbed-wire fence around the Government House.
According to Thai Rath daily newspaper, Prayut left the Government House earlier than usual.
The demonstrations were ignited back in February when the constitutional court banned opposition party Future Forward, which was popular among students. The emergence of the COVID-19 pandemic and imposition of a lockdown in early April hampered the protest movement. However, the pandemic has also affected the economic situation in the country and deepened public resentment with the authorities. The protesters demanded political reforms, namely the revision of the monarch's immunity from prosecution, and called on the prime minister, who had been the chief of the Thai army before the 2014 coup, to step down.