On May 22, 1970, Prime Minister Lon Nol declared martial law across the country.
On May 22, 1993, Prince Norodom Sihanouk returned from Cambodia after 6 months in Beijing for medical treatment, He arrived on the eve of the UNTAC sponsored elections.
On May 23, 1969, Cambodia signed the Vienna Convention on the Law of Treaties (VCLT). Cambodia remains one of 15 states (including the USA) that signed, but have not ratified the treaty.
On May 23, 1993, elections for the Constituent Assembly were opened and ran until May 28. The United Front for an Independent, Neutral, Peaceful, and Cooperative Cambodia (FUNCINPEC) headed by Prince Norodom Ranariddh won 58 out of 120 seats, while the CPP headed by Hun Sen won 51 seats.
On May 24, 1950, the government of the United States announced it would initiate a program of economic aid to the States of Cambodia, Laos, and Vietnam, in order to assist Cambodia, Laos, and Vietnam to restore stability and pursue their peaceful and democratic development. “The Government of the United States recognizes that this American assistance will be complementary to the effort made by the three Associated States and France, without any intention of substitution. American aid is designed to reinforce the joint effort of France and the Governments and peoples of Cambodia, Laos, and Vietnam, on whom rests the primary responsibility for the restoration of security and stability.”
Robert Blum had been appointed Chief of the United States special economic mission to Cambodia, Laos, and Vietnam. Blum- a secretive character with top links to espionage agencies- was dubbed by French military commander in Indochina, General Jean Delattre as “the most dangerous man in Indochina” .
On May 24, 1969: Ratanakiri and Stung Treng were considered as lost to communist forces
On May 24, 1975, Vietnamese forces recapture Phu Quoc and Tho Chu from the Khmer Rouge.
On May 25, 1970, the U.S. government decided to provide military assistance to Cambodia. Operation Bin Thay II (Tame the West) in NE Cambodia ended. U.S./ARVN losses were 43 killed while PAVN/VC losses were 212 killed and 7 captured and 859 individual and 20 crew-served weapons captured.
On May 24, 1970, a 4,000-man ARVN armored task force linked up with FANK troops and retook the town of Kampong Speu, which had fallen to communist forces, after a request from Lon Nol.
On May 25, 1978, the Khmer Rouge leadership purged the East Zone
On May 27, 1978, records from S-21 (Toul Sleng) showed that 582 inmates died in a single day.
On May 25, 1992, Cambodian Public Bank Plc (Campu Bank) opened for business.
On May 26, 1961, the government of Thailand preliminary objections to the International Court of Justice’s jurisdiction over the Preah Vihear case were rejected in a Judgment by the court.