So I was recently reading about the surprising and absurd instance of 1979 when French commandos had to briefly convert to Islam to be allowed into the holy city of Mecca in order to relieve its siege by al ikhwan extremists on behalf of the Saudi government. My question is why did the Saudi government resort to this? Surely it would be a massive PR failure for the Saudis and the broader Arab and Islamic worlds, to be seen relying on a former imperialist western power to protect their cultural heritage? Furthermore, why the French? From my own knowledge before the Saudis Mecca was traditionally in the British and ottoman Spheres of influence. It has no historical connection to France and France has little military presence there.
While it's true that the Groupe d'intervention de la Gendarmerie Nationale, the special operations unit of the French national police, was involved in ending the Grand Mosque siege, they weren't the primary force on the field: in fact, only three GIGN operators deployed to Saudi Arabia in November 1979, at the explicit request of the Saudi interior ministry.
As for why Saudi officials turned to France for assistance, there are a couple of reasons: one is that in 1979, there were as yet relatively few capable dedicated counter-terrorist forces in the world. GIGN, the British SAS' counter-terrorism wing and Germany's GSG-9 were all established in the mid-1970s, in the aftermath of the massacre at the Munich Olympics; the United States Army's Delta Force was only created in 1977, and the FBI's Hostage Rescue Team in 1983. GIGN, at the time, was (and remains) one of the world's premier counter-terrorist units — so it wasn't, on its face, a particularly strange place for the Saudis to turn in such circumstances.
The request also had a lot to do with the relationship between Alexandre de Marenches, the then-director of SDECE, the French external intelligence service. Throughout the 1970s, de Marenches sought to develop friendly relationships at the highest levels of the Saudi government — up to and including King Faisal. France became a major supplier of arms to the kingdom, and the French military and intelligence services provided advisory and training support to their Saudi counterparts.
In particular, de Marenches found a friend in Prince Turki bin Faisal, the king's son and (at the time of the siege), the newly-appointed chief of the Mukhabarat (General Intelligence Directorate). Turki and de Marenches were heavily involved in the formation of the 'Safari Club', a covert partnership between the intelligence services of France, Saudi Arabia, Egypt, Iran and Morocco.
In his book on the Grand Mosque siege, Yaroslav Trofimov also attributes an important role in seeking French aid to Prince Nayef bin Abdul-Aziz, Turki's uncle and Minister of the Interior. Nayef had apparently witnessed a striking display of GIGN's tactical prowess at a demonstration in France in the spring of 1979 — led by Paul Barril, deputy commander of GIGN and one of the officers who would be deployed to Saudi Arabia in November. According to Trofimov, "once Prince Turki's phone call to Count de Marenches opened contacts on possible French help in the Mecca affair, the Saudis specifically requested the GIGN."
Seeking a nonlethal approach to incapacitating the militants holding the Grand Mosque, the Saudi government asked GIGN to design a plan of attack using gas, and to oversee the operation — from Taef, a neighbouring city. They were not to be allowed to enter Mecca. Trofimov writes:
In spite of this prohibition, Barril, by his own account, briefly sneaked into the holy city and into the Grand Mosque itself before the attack on the compound began. Some U.S. officials concur with this version.
Barril's two comrades in arms and [GIGN commander Christian] Prouteau are adamant that this never happened. The French role in the Mecca affair, they insist, was strictly limited to providing equipment and training in Taef and its vicinity. According to them, neither Barril nor any other French soldier set foot on Mecca's sacred ground during the siege.
Even if the French captain did visit Mecca during the crisis, it was in a strictly advisory capacity. No French commandos engaged in actual combat on Saudi soil.
The assault on the mosque was carried out by the Saudi National Guard — though some claim (without much in the way of compelling evidence) that commandos from Pakistan's Special Service Group were also involved. Lawrence Wright, in his otherwise excellent The Looming Tower, gives a brief and rather flimsy account of the siege that includes both the ad-hoc conversion to Islam and has the commandos directly involved in the assault:
A team of three French commandos from the Groupe d'Intervention de la Gendarmerie Nationale (GIGN) arrived in Mecca. Because of the prohibition against non-Muslims entering the holy city, they converted to Islam in a brief, formal ceremony. The commandos pumped gas into the underground chambers, but perhaps because the rooms were so bafflingly interconnected, the gas failed and the resistance continued.
It's unclear what Wright is basing that account on — other than widespread rumour and speculation that has circulated in the 30 years since the siege — and Trofimov has little to say about the topic of conversion; only that it apparently came up in conversation between the GIGN operators and their Saudi liaisons, not that it ever actually happened.