Ahmad bin Yahya Hamidaddin (Arabic: أحمد بن يحيى حميد الدين; June 18, 1891 – September 19, 1962[1]) was the penultimate king of the Mutawakkilite Kingdom of Yemen, who reigned from 1948 to 1962.

His full name and title was H.M. al-Nasir-li-Dinullah Ahmad bin al-Mutawakkil 'Alallah Yahya, Imam and Commander of the Faithful, and King of the Mutawakkilite Kingdom of the Yemen.

[5] Like his father, Ahmad was profoundly conservative, but nevertheless forged alliances with the Soviet Union, Communist China and Nasserist Egypt, all of which provided economic and military aid to the kingdom.

In December 1916, during World War I, Ahmad launched a military revolt against his father,[8] after having sought aid from the British-allied Idrisid Emirate of Asir the preceding month.

Ibrahim had been in open revolt against his father for a year having fled and joined a group called "Free Yemenites" in the Aden Protectorate in 1946.

[15] The plan to simultaneously murder Ahmad in Ta'izz failed, and he advanced on Hajjah where loyal tribes supplied his forces.

Yahya's third son, Hasan Hamid al-Din, then governor of the southern province of Ibb but beloved by the northern tribes, rallied those forces to his brother Ahmad's cause, entered Sana'a and ended the short-lived revolutionary government.

The new Imam Ahmad, all-Nasir li-Din Allah ("the Protector of God's Religion") would rule from Ta'izz, while Sana'a was given over to looters.

It was said that every detail, no matter how small or trivial, had to be approved by the Imam, even for a government truck to be moved in Ta'izz or mules to receive fodder.

[22] The museum which was once his palace (now no longer open to the public) supposedly contains his "bizarre collection of hundreds of identical bottles of eau de cologne, Old Spice and Christian Dior, an electronic bed, a child's KLM handbag, projectors, films, guns, ammunition and swords ... passports, personalized Swiss watches and blood-stained clothes.

[20] His one abiding policy goal as Imam (aside from his reactionary position on government) was to drive the British from Aden and recover the protectorate for "Greater Yemen," as his father saw it.

[25] Rhetoric turned to border skirmishes and on March 26, 1955, Ahmad charged Britain with having killed a number of Yemenis in a "brutal attack" in southern Yemen.

Three days later from their respective capitals Egypt, Syria and Saudi Arabia issued a joint decree announcing an agreement to "strengthen the Arab structure politically, militarily and economically.

[33] Imam Ahmad permitted his Jewish subjects to immigrate to Palestine during the height of the Arab–Israeli conflict, in which he committed a small expeditionary force, in 1948.

[34] In May 1949, Imam Ahmad announced that any Jew who wanted to leave Yemen would be permitted to do so, on three conditions: that he reimburse any debts, first and foremost, the poll-tax known as the jizya; that he sell his property; and, that if he were a skilled artisan, that he teach his profession to local Yemeni Arab citizens.

[36] His announcement prompted a mass exodus of Jews, dubbed "The Immigration 'On Eagles' Wings'," which took place from June 1949 until September 1950.

Ahmad bin Yahya's oldest son, Muhammad al-Badr was proclaimed Imam and King[37] and took the title of al-Mansur, but a week later rebels shelled his residence, Dar al-Bashair, in the Bir al-Azab district of Sana'a.

A coup led by a group of nationalist officers deposed al-Badr, and the Yemen Arab Republic (YAR) was proclaimed under the leadership of Abdullah al-Sallal.