Vichy France, which was a client state of Germany, nominally maintained the French protectorate over Cambodia and other parts of Indochina during most of the Japanese occupation.

The Vichy government signed an agreement with Japan to allow the Japanese military transit through French Indochina and to station troops in Northern Vietnam up to a limit of 25,000 men.

[3] Meanwhile, the Thai government, under the pro-Japanese leadership of Field Marshal Plaek Phibunsongkhram, and strengthened by virtue of its treaty of friendship with Japan, took advantage of the weakened position of France, and invaded Cambodia's western provinces to which it had historic claims.

On 20 July 1942, there was a major anti-French demonstration in Phnom Penh after a prominent monk, Hem Chieu, was arrested for allegedly preaching seditious sermons to the colonial militia.

[2] Pach Chhoen was a respected Cambodian intellectual, associated with the Buddhist Institute and founder of Nagaravatta, the first overtly political newspaper in the Khmer language in 1936, along with Sim Var.

The aim was to revive the flagging support of local populations for Tokyo's war effort by encouraging indigenous rulers to proclaim independence.

However, Son Ngoc Thanh, another of the men behind Nagaravatta who had fled to Japan following the 1942 anti-French demonstrations, had returned in April 1945 to serve as foreign minister.