When Trinquier's two years of compulsory military service came to an end, he decided to remain in the army and was transferred to the active officers’ school of Saint-Maixent, from which he graduated in 1933 as a second lieutenant. He now joined the colonial infantry. After some time with the 4th Senegalese Tirailleur Regiment at Toulon, he embarked on a ship bound for Indochina on 11 May 1934. He was first stationed at Kylua, near Lang Son, in Tonkin (Northern Vietnam). He then took command of a French outpost at Chi Ma on the Chinese border. Trinquier returned to France in 1936 and was assigned to the 41st Colonial Infantry Machine-gun Regiment (41e Régiment de Mitrailleurs d’Infanterie Coloniale, 41e RMIC) at Sarralbe, where he commanded a company until he was sent to China in early August 1938.