The idea of appointing Mohammed Al-Badr – to be the Crown Prince- which promoted by the most prominent figures of the 1948 revolutionaries, after their release from the prisons of Hajjah, and at the request of Imam Ahmad, in which they collected the signatures for it, became then a wedge in the side of the Hameed al-Din family. However, the brother of the Imam Al-Hassan, who was known for his extremism, was strongly opposed to it and believed that it will eliminate their rule: "if the mandate of the Covenant is one of the pillars and characteristics of the hereditary monarchy, which its opponents used to reject it and refuse the monarchy regime. They always continued to cling to the Zaidi Imamate system, which rejects the principle of inheritance in governance."
During the months of June and July 1954, the confrontation between the supporters of Al-Badr and the supporters of Al-Hassan reached its climax, in which the organs of power, newspapers, mosques, festivals and celebrations were used. Consequently, in the face of pressure, Imam Ahmad was forced to stop the campaign, freeze the problem, and prevent delving into it, while waiting for another way to solve it. So, there was nothing left for him but the Arab mediation. After that, King Saud arrived in Sana'a and tried to persuade the princes to pledge allegiance to Al-Badr as the crown prince, but his attempt failed.
The atmosphere was tense between the two camps, and it was said that a plot was being prepared to kill the imam in Sana'a, which made him to return to Taiz urgently. Then he quickly worked to get Al-Hassan out of Yemen, under the pretext of participating in the conference of the Arab governments in Cairo, before he exiled him to the United States under the name of Yemen’s delegate to the United Nations. On the other hand, he summoned his brother Abdullah to Taiz, and appointed him as Minister of Foreign Affairs and a special advisor, to absorb the anger of the rest of the divided princes.
In these circumstances, Colonel Ahmed Al-Thulaya (the army commander) appeared on the scene of events, "who was aspiring to a revolution that would depose and remove Ahmed from the power and pave the way for a non-tyrannical imam,", his opinion settled on Saif Al-Islam Abdullah, who was in contact with him. He showed him his complaints about the situation, so this complaint coincided with a latent desire in Al-Thulaya's soul.
Furthermore, Abdullah had been joined by most of the members of the royal family, such as his brother Al-Abbas and the prince Al-Hassan Ibn Saif Al-Islam Ali. In the meantime, Al-Thulaya had prepared a plan, including the capture of Al-Badr and the replacement of the military groups in Al-Qahira Castle and Dar Al-Nasr in Saber in Taiz. Nevertheless, before the plan was executed, friction occurred between some soldiers and the people of Al-Hawban in Taiz, in what is known as the Al-Hawban Incident. On Wednesday, March 30, 1955, some of the regular soldiers came out of their camp to get firewood, and a dispute broke out between them and some of the people of Al-Hawban, in which one soldier was killed, and in another story, two soldiers. Thus, the soldiers returned to cry out to the army, which then went out looting the village of Al-Hawban, burning it, and killing whoever it found, and then returned to its barracks after the sunset on the same day.
However, when the anger subsided and they came back to their senses, they knew that they had crossed their limits and that the imam would take revenge on them. So, they began to think of fleeing. Nevertheless, Al-Thulaya and Murshid Al-Suraihi came to them and told them that the one who insulted you and caused you to commit these acts against the poor citizens was the imam who forced you to go out for firewood, so a dispute arose between you and the citizens, and for now that what you have done is done, you will not escape from severe punishment, and we, as officers, are ready to enter into a battle with the imam for your sake. Therefore, instead of fleeing abroad and becoming homeless, come and besiege the palace and force the imam to cede to his brother Abdullah, who promised to provide your salaries, protect you, and treat you as the armies of the world. Thus, the soldiers were convinced and excited. On Thursday, March 31, 1955 (at six o'clock in the morning), the Army laid siege to the royal palace in Al-Ardi and Maqam (the residence palace), occupied the government buildings, opened ammunition stores, distributed weapons to those without weapons, seized cars and the airport, cut telegraph and telephone wires, and occupied the radio station. The soldiers shouted, demanding the imam cede to his brother Abdullah.
Lieutenant Colonel Al-Thulaya summoned the people of concern and all members of the Mutawakkilite government, including: Al-Numan, Al-Iryani, the prince of Al-Bayda Mohammed bin Abdullah Al-Shami, Mohammed Al-Thari, Hammoud Al-Washli, Zaid Aqabat, Abdullah Al-Shammahi, Yahya Al-Siyaghi, Ahmed Zabara, Yahya Al-Kibsi, Yahya Mohammed Basha Al-Mutawakkil, the prince of the Taiz Army Mohammed Al-Houthi, Mohammed bin Ali Al-Mujahid, Abdullah Abdullillah Al-Aghbari, Ahmed bin Mohammed Al-Mahdi, Qasim bin Ibrahim, Mohammed bin Hassan Abdul Qadir, and Mohammed bin Qasim bin Al-Hadi, and then Abdullah was summoned from his room in the palace. After that, he came and started communicating with Imam Ahmad. However, the Imam did not give up or respond to their demands.
The army, led by Al-Suraihi, fired bullets at the imam's room in the palace for about five minutes. The artillery also struck the balconies of the palace, while shouting for the imam's abdication and pledging allegiance to Abdullah, threatening that in the event of non-response, they would blow up the imam and his palace and crush those gathered in the courtyard of the Al-Ardi. So the prince of the army, Mohammed Al-Houthi, and the prince of Al-Bayda, Mohammed Al-Shami, went and stopped firing and called Imam Ahmed, who answered them calmly that he is abdicated, and handed them a paper that contained some kind of deception, in which he said that he had abdicated to his brother from the business and that it was like moving the ring from right to left.
Those in charge of the coup continued their position, reassured the internal situation, and saw that most of the problems had been solved by Ahmed's abdication without bloodshed, and most of the responsible figures were inclined to Abdullah. There was no obstacle but Al-Badr, and for that, Al-Numan went to him. On the other hand, their attention was focused on the position of Al-Hassan, who is abroad, and the position of King Saud, the Arab Republic, and the Arab League. They formed three delegations, and one of the missions of the delegation to Al-Hassan was to persuade him to pledge allegiance to Abdullah and to freeze his activity in his place abroad until things stabilized. The delegations were prepared, and the necessary work was done for their travel after Friday prayer.
But on Friday morning, everything had changed, and that was because Al-Badr succeeded in joining Al-Nu’man to him, and traveling with him to Hajjah, crying out to the tribes. Thus, things turned upside down, and imam Ahmad issued a publication informing the people that his son Al-Badr had ascended to Hajjah , and the tribes there gathered around him, and that he did not abdicate. So, this had the effect of magic in changing the situation completely.
Consequently, only three days passed until things were moving in the direction of the imam's control of the situation, after he was able to inveigle the irregular soldiers, the military garrisons in the castle, Saber mountain, Saalah, and Al-Jahmaliyah with a lot of money. So, the artillery began striking the army barracks and the command headquarter in Al-Ardi, instead of striking the Maqam.
The war continued on Tuesday night and day. At midnight on Wednesday, Colonel Al-Thulaya and Murshid Al-Suraihi fled. At the same time, the soldiers had also fled in groups because of what they suffered from the artillery shelling. Al-Suraihi escaped and fled to Aden. On the other hand, when Colonel Al-Thulaya ended up in the village of Al-Luwazim in Jabal Saber, the citizens arrested him. As for imam Abdullah and those with him, they sent a letter to Imam Ahmed announcing their surrender, and so he ordered their imprisonment at the headquarter of the Ministry of Foreign Affairs before they were sent to Hajjah prison.
Lieutenant Colonel Al-Thulaya was executed in Al-Ardi in Taiz, hours after his arrest (at noon on Wednesday, April 6). One week later, on Wednesday, April 13, the imam's brothers Abdullah and Al-Abbas were executed in Hajjah. Further, during the period between April 6 and April 24, 16 army officers and civilian figures, who stood by Al-Thulaya and Abdullah, were executed.