The country lost control of Cambodia and Laos and ceding a few southern provinces in 1889-1909, suffering from the imperial designs of the British and especially French.

[1] In July 1917, despite the fears of some members of the royal government, King Rama VI declared war on Austria-Hungary and Germany.

Therefore, the Thai forces interned and then confiscated at least 12 ocean-going ships of the North German Line as war reparations.

[1][2] In 1918, the forces arrived, and aviation personnel began training at the French Army Flying Schools at Avord and Istres.

The Thai pilots flew their first sorties in the last weeks of the war, although other sources claim that they finished their training too late to take part.

[3] The Siamese Expeditionary Forces (SEF) set up their headquarters at the Hotel zum Löwen by the train station.

The Corps was responsible for maintaining public order, demanding respect from the German population, but behaved with restraint.

[2] A war memorial, described as a Srivijaya Buddhist stupa, was erected in honor of the Thai soldiers and is located at the northwestern corner of Sanam Luang park in central Bangkok.