On 19 September 1962, King Iman Amhed of Yemen died. His son, Crown Prince Saif al-Islam Mohammed al Badr assumed the crown. However, a rebel faction led by Colonel Abdullah al-Sallal proclaimed a "Free Yemen Republic" on 27 September 1962. As a consequence, civil war broke out, and the Soviet Union and Egypt quickly recognized the new republican government on 29 September.
King Faisal of Saudi Arabia sent troops to aid the royalist forces, while Abdul Gamal Nasser, the President of Egypt, sent 60,000 troops to support Colonel Abdullah al-Sallal. In 1963, Saudi Arabia and Egypt agreed to a ceasefire and troop withdrawal. The United Nations (UN) established the UN Yemen Observation Mission (UNYOM) to ensure that these terms were observed. However, the ceasefire was violated twice the following year, and neither the Saudis nor Egyptians withdrew their forces.
Finally, a lasting ceasefire was negotiated on 24 August 1965. The forces of Saudi Arabia and Egypt were withdrawn, and a plebiscite was implemented to determine the future government of Yemen. UNYOM consisted of 190 military observers. The Canadian contingent to this mission was 36 officers and men.