The North Yemen civil war, also known in Yemen as the 26 September Revolution, was a civil war fought in North Yemen from 1962 to 1970 between partisans of the Mutawakkilite Kingdom and supporters of the Yemen Arab Republic. The war began with a coup d'état carried out in 1962 by revolutionary republicans led by the army under the command of Abdullah al-Sallal. He dethroned the newly crowned King and Imam Muhammad al-Badr and declared Yemen a republic under his presidency. His government abolished slavery in Yemen. The Imam escaped to the Saudi Arabian border where he rallied popular support from northern Zaydi tribes to retake power, and the conflict rapidly escalated to a full-scale civil war.
On the royalist side, Jordan, Saudi Arabia, and Israel supplied military aid, and Britain offered covert support. The republicans were supported by Egypt (then formally known as the United Arab Republic or UAR) and were supplied warplanes from the Soviet Union. Both foreign irregular and conventional forces were also involved. Egyptian President Gamal Abdel Nasser supported the republicans with as many as 70,000 Egyptian troops and weapons. Despite several military actions and peace conferences, the war sank into a stalemate by the mid-1960s. Egypt's commitment to the war is considered to have been detrimental to its performance in the June 1967 Six-Day War against Israel. Once the Six-Day War began, Nasser found it increasingly difficult to maintain his army's involvement in Yemen and began to pull out his forces. The surprising removal of Sallal on November 5 by Yemeni dissidents, who were supported by republican tribesmen, resulted in an internal shift of power in the capital, as the royalists were approaching from the north.
The new republican government was headed by Abdul Rahman al-Eryani, Ahmed Noman, and Mohamed Ali Uthman, all of whom promptly resigned or fled the country. The capital was left under the control of Prime Minister Hassan al-Amri. The 1967 siege of Sana'a became the turning point of the war. The remaining republican Prime Minister succeeded in keeping control of Sana'a and, by February 1968, the royalists lifted the siege. Clashes continued in parallel with peace talks until 1970, when Saudi Arabia recognized the Republic, and a ceasefire came into effect.
Egyptian military historians refer to the war in Yemen as their "Vietnam [War]". Historian Michael Oren (former Israeli Ambassador to the U.S.) later wrote that Egypt's military adventure in Yemen was so disastrous that the United States' actions in the continuing Vietnam War could easily have been dubbed "America's Yemen".
Imam Ahmad bin Yahya inherited the Yemeni throne in 1948. In 1955, Iraq-trained Colonel Ahmad Thalaya led a revolt against him. A group of soldiers under his command surrounded the royal palace of Al Urdhi at Taiz—a fortified stronghold where the Imam lived with his harem, that also housed the royal treasure, an arsenal of modern weapons, and a contingent of 150 palace guards—and demanded that Ahmad abdicate. Ahmad agreed, but demanded that his son, Muhammad al-Badr, succeed him. Thalaya refused, preferring the king's half-brother, the Emir Saif el Islam Abdullah, the 48-year-old foreign minister. While Abdullah began forming a new government, Ahmad opened the country's coffers and secretly began buying off the Thalaya's soldiers. After five days, the number of soldiers besieging the palace was reduced from 600 to 40. Ahmad then came out of the palace, wearing a devil's mask and wielding a long scimitar, terrifying the besiegers. He slashed two sentries dead before exchanging the sword for a sub-machine gun and leading his 150 guards onto the roof of the palace to begin a direct attack on the rebels. After 28 hours, 23 rebels and 1 palace guard were dead, and Thalaya gave up. Abdullah was later reported executed, and Thalaya was publicly decapitated.
In March 1958, al-Badr arrived in Damascus to tell President Nasser of Yemen's adherence to the United Arab Republic (UAR). However, Ahmad was to keep his throne and his absolute power, and the arrangement constituted only a close alliance. In 1959, Ahmad went to Rome for treatment of his arthritis, rheumatism, heart trouble and, reportedly, drug addiction. Fights erupted between tribal chieftains, and al-Badr unsuccessfully tried to buy off the dissidents by promising "reforms", including the appointment of a representative council, more army pay, and promotions. Upon his return, Ahmad swore to crush the "agents of the Christians". He ordered the decapitation of one of his subjects and the amputation of the left hand and right foot of 15 others as punishment for the murder of a high official the previous June. Al-Badr was only rebuked for his leniency, but the Yemeni radio stopped broadcasting army officers' speeches, and talks of reforms were silenced.
In June 1961, Ahmad was still recovering from an assassination attempted four months prior, and moved out of the capital, Taiz, into the pleasure palace of Sala. Defense and foreign minister, Badr became acting prime minister and interior minister. Despite being crown prince, al-Badr still needed the Ulema in San'a to ratify him. Al-Badr was not popular with the Ulema due to his association with Nasser, and the Ulema had refused Ahmad's request to ratify Badr's title. Imam Ahmad died on September 19, 1962, and was succeeded by his son, Muhammad al-Badr. One of al-Badr's first acts was to appoint Colonel Abdullah Sallal, a known socialist and Nasserist, as commander of the palace guard.
Nasser had looked to a regime change in Yemen since 1957 and finally put his desires into practice in January 1962 by giving the Free Yemen Movement office space, financial support, and radio airtime. Anthony Nutting's biography of Nasser identifies several factors that led the Egyptian president to send expeditionary forces to Yemen, including the unraveling of the union with Syria in 1961, which dissolved his UAR in all but name, damaging Nasser's prestige. A quick, decisive victory in Yemen could help him recover leadership of the Arab world. Nasser was also keen to maintain his reputation as an Arab nationalist, setting his sights on expelling British forces from South Yemen, including Britain's presence in the strategic port city of Aden.
Mohamed Heikal, a chronicler of Egyptian national policy and decision making, and confidant of Nasser, wrote in For Egypt Not For Nasser, that he had engaged Nasser on the subject of supporting the coup in Yemen. Heikal argued that Sallal's revolution could not absorb the massive number of Egyptian personnel who would arrive in Yemen to prop up his regime, and that it would be wise to consider sending Arab nationalist volunteers from throughout the Middle East to fight alongside the republican Yemeni forces, suggesting the Spanish Civil War as a template from which to conduct events in Yemen. Nasser refused Heikal's ideas, insisting on the need to protect the Arab nationalist movement. Nasser was convinced that a regiment of Egyptian Special Forces and a wing of fighter-bombers would be able to secure the Yemeni republican coup d'état.
Nasser's considerations for sending troops to Yemen may have included the following:
Impact of his support to the Algerian War of Independence from 1954 to 1962
Syria leaving Nasser's UAR in 1961
Taking advantage of a breach in British and French relations, which had been strained by Nasser's support for the FLN in Algeria, and primarily as an effort to undermine the Central Treaty Organization (CENTO), which caused the downfall of the Iraqi monarchy in 1958
Confronting imperialism, which Nasser saw as Egypt's destiny
Guaranteeing dominance of the Red Sea from the Suez Canal to the Bab-el-Mandeb strait
Retribution against the Saudi royal family, whom Nasser felt had undermined his union with Syria.
At least four plots were going on in San'a. One was headed by Lieutenant Ali Abdul al Moghny. Another one was conceived by Sallal. His plot merged into a third conspiracy prodded by the Hashid tribal confederation in revenge for Ahmad's execution of their paramount sheik and his son. A fourth plot was shaped by several young princes who sought to get rid of Badr but not the imamate. The only men who knew about those plots were the Egyptian chargé d'affaires, Abdul Wahad, and Badr himself. The day after Ahmad's death, Badr's minister in London, Ahmad al Shami, sent him a telegram urging him not to go to San'a to attend his father's funeral because several Egyptian officers, as well as some of his own, were plotting against him. Badr's private secretary did not pass this message to him, pretending he did not understand the code. Badr may have been saved by the gathering of thousands of men at the funeral. Badr learned of the telegram only later.