Thailand. (Laotian Civil War). 1971. Stamp-less envelope addressed to Bangkok cancelled by Nan date stamp '14th Sept 2514 (1971)' with framed 'Royal Thai Army Border Patrol' hand-stamp and 'Censor/ Checked' cachet, signed by the Commanding Officer with Bangkok GPO arrival on reverse and slogan postmark.
Royal Thai Army troops had been in Dai Phu Kha National Park (Nan Province) on the Thai - Laos border as part of 'Operation Phalat' a military offensive of the Laotian Civil War.