Some of the National United Front of Democracy Against Dictatorship (UDD) members, coming in 100 cars, visited the 11th Infantry Regiment King's Guard in Bangkok's Bang Khen area Saturday morning.
The wanted to submit a letter calling for soldiers to not support violence or a coup and to support democracy.
The regiment's representative accepted the letter and the caravan left for Imperial World shopping centre in Lat Phrao.
They were preparing to join a big rally of the red shirts at Khao Talo in Pattaya on Saturday evening.
Jatuporn Prompan, the new chairman of the UDD, called the planned Pattaya rally the countdown to Bangkok of the red shirts.