In the 1920s and 1930s, Ahmad assisted his father in putting together his kingdom through strategy, diplomacy, tribal warfare and intrigue.
Ahmad was appointed governor of Ta'izz from 1918 to 1948.
In 1927 he was named wali ahad, effectively the crown prince.

From his father, Ahmad learned a deep distrust for the new and a profound aversion to any change in medieval methods of governance.
While governor he surrounded himself with reformers, however.
He always tried to keep the factions close to him but his volatile temper often betrayed him.
In 1944 at his court in Ta'izz, he was heard to exclaim, "I pray God I do not die before I colour my sword here with the blood of these modernists."
The outburst caused Ahmad Muhammad Nu'man, Muhammad al-Zubayri and other future "liberals" (in the Yemen sense of Yemeni independents and moderate reformers) to quit his court and flee to Aden.
There they founded the Free Yemeni Movement.

His arbitrary and erratic behavior, however, did not diminish his popularity in Ta'izz.
While governor he razed the tomb of Ibn Alwan without any protest from Shafi'i clerics.
He was not a doctrinaire Zaidi, however.
In 1952 he imprisoned in the notorious Hajjah dungeons Zaidis who attacked a cleric in Ibb for a sermon praising the three caliphs before Ali.
Although his soldiers were Zaidi and the population of Ta'izz Shaff'i, a British observer found "there is almost universal loyalty to the Yemen, if not to the person of the Imam ..."
In February 1948 Yahya, three of his sons and his chief adviser were assassinated in a coup, in which the religious leader Abdullah bin Ahmed al-Wazir was proclaimed Imam.
Yahya's son (and Ahmad's brother) Ibrahim bin Yahya was appointed head of the "constitutional government."
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.
The plan to simultaneously murder Ahmad in Ta'izz failed, and he advanced on Hajjah where loyal tribes supplied his forces.

Abdullah was established in Sana'a.
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.
Ahmad rewarded him with the offices of prime minister and governor of Sana'a.
 With the support of the northern tribes as well as Ahmad's Shafi'i stronghold in Ta'izz, the conspirators were rounded up in four weeks.
Most were beheaded.
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.
Unaffiliated liberals were also swept up in the net.
About thirty were beheaded, while the rest were left in dungeons.
Most were released in two years, often after writing obsequious flattery of the imam, but others were left in prison for much longer.
In the 1920s and 1930s, Ahmad assisted his father in putting together his kingdom through strategy, diplomacy, tribal warfare and intrigue. Ahmad was appointed governor of Ta'izz from 1918 to 1948. In 1927 he was named wali ahad, effectively the crown prince.
From his father, Ahmad learned a deep distrust for the new and a profound aversion to any change in medieval methods of governance. While governor he surrounded himself with reformers, however. He always tried to keep the factions close to him but his volatile temper often betrayed him. In 1944 at his court in Ta'izz, he was heard to exclaim, "I pray God I do not die before I colour my sword here with the blood of these modernists." The outburst caused Ahmad Muhammad Nu'man, Muhammad al-Zubayri and other future "liberals" (in the Yemen sense of Yemeni independents and moderate reformers) to quit his court and flee to Aden. There they founded the Free Yemeni Movement.
His arbitrary and erratic behavior, however, did not diminish his popularity in Ta'izz. While governor he razed the tomb of Ibn Alwan without any protest from Shafi'i clerics. He was not a doctrinaire Zaidi, however. In 1952 he imprisoned in the notorious Hajjah dungeons Zaidis who attacked a cleric in Ibb for a sermon praising the three caliphs before Ali. Although his soldiers were Zaidi and the population of Ta'izz Shaff'i, a British observer found "there is almost universal loyalty to the Yemen, if not to the person of the Imam ..."
In February 1948 Yahya, three of his sons and his chief adviser were assassinated in a coup, in which the religious leader Abdullah bin Ahmed al-Wazir was proclaimed Imam. Yahya's son (and Ahmad's brother) Ibrahim bin Yahya was appointed head of the "constitutional government." 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. The plan to simultaneously murder Ahmad in Ta'izz failed, and he advanced on Hajjah where loyal tribes supplied his forces.
Abdullah was established in Sana'a. 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. Ahmad rewarded him with the offices of prime minister and governor of Sana'a.  With the support of the northern tribes as well as Ahmad's Shafi'i stronghold in Ta'izz, the conspirators were rounded up in four weeks. Most were beheaded. 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. Unaffiliated liberals were also swept up in the net. About thirty were beheaded, while the rest were left in dungeons. Most were released in two years, often after writing obsequious flattery of the imam, but others were left in prison for much longer.
Ahmad bin Yahya