A crowded market in the heart of the capital was the chosen target of the first suicide bombing in Chad's history. In a split second, 15 people were killed and 80 maimed.
It soon became clear that a man clad in a burqa had carried out the attack, passing through the checkpoint outside the market by concealing his explosives beneath the all-enveloping canopy.
The government of the West African country responded last July with a measure that elsewhere might have been seen as draconian: it simply banned the burqa.
Anyone seen wearing one would be arrested, promised Kalzeube Pahimi Deubet, the prime minister, and those garments on sale in the market would be burnt. This sudden bonfire of burqas was an essential security precaution designed to prevent terrorists from “camouflaging” themselves, he added.
Boko Haram, the bloodstained Islamist movement that emerged in northern Nigeria and now menaces at least four West African countries, soon claimed responsibility for the bombing.
Other countries in Boko Haram’s line of fire were quick to follow Chad’s example. The following month, Cameroon also banned the burqa in its northern region, the area where Boko Haram attacks have driven tens of thousands from their villages.
Niger was next, banning the burqa in its southern region which borders Boko Haram’s main killing ground in Nigeria.
Most of the people of Chad and Niger are Muslims: they comprise 53 per cent and 80 per cent of their populations respectively. In Cameroon, Muslims are a minority of 25 per cent nationally, but a majority in the region where the burqa was banned.
In total, these three countries are home to 36 million Muslims. Yet there was scarcely any public opposition to the ban – and the prohibition has largely been observed and enforced, at least in urban areas where the security forces are present.
“I share the surprise about the lack of a backlash,” said Virginia Comolli, a research fellow at the International Institute for Strategic Studies. “I also would have expected a bit more of a backlash against this – but it didn’t happen.”
Ms Comolli, the author of Boko Haram: Nigeria’s Islamist Insurgency, said the ban was “significant because it shows how seriously these countries are treating the problem. They consider the threat is high enough for them to take this unusual step".
As for why there had been no significant public opposition, Ms Comolli said: “For me, it’s a sign of the desperation of the people in the face of Boko Haram’s threat that they are prepared to accept a step like this.”
The decision taken by Chad, Niger and Cameroon has since received the backing of West Africa as a whole. Last December, a summit of all 15 members of the Economic Community of West African States (ECOWAS) formally endorsed a ban on “clothing that prevents the clear identification of persons”.
Today, 15 countries with a total Muslim population of 181 million are pledged to support banning the burqa, even if they will not necessarily pass such a law themselves.
Two other countries, Guinea and Senegal, are considering whether to proceed with a legal prohibition. Last November, Abdoulaye Daouda Diallo, the Senegalese interior minister, said that he would support outlawing the burqa as a security precaution. “If the ban is necessary, the measure will be applied in Senegal,” he said.
No terrorist attack has yet occurred in Senegal, but Mr Diallo said: “We must work on prevention, because form the time the terrorism is installed, it becomes very difficult to eradicate.”
About 95 per cent of Senegal’s 14 million people are Muslims, yet the burqa has always been a rare sight on the streets of the capital, Dakar, and there was no significant opposition to the suggestion of a ban.
But Nigeria remains the great exception. Although Muhammadu Buhari, the Nigerian president, endorsed the ECOWAS statement, there is no suggestion that he might impose a ban at home. In northern Nigeria, the Islamist radicalism symbolised by the burqa has such deep roots that any attempt at prohibition would risk provoking more unrest than it would avoid.
Elsewhere in West Africa, a moderate version of Islam, in tune with local custom, still holds sway, making it possible for governments to outlaw the burqa.
In Nigeria, by contrast, a cycle of radicalisation has been underway for decades. “Boko Haram has local roots,” said Ms Comolli. “If you look at the history of Islam in northern Nigeria, Boko Haram doesn’t really represent an anomaly: it’s a continuation of a local cycle or trajectory.”
Radical Islamists want, above all, to spread their harsh and austere message as widely as possible. Ironically, their bloodsoaked campaign has served to encourage a ban on the very clothing which they wish to make compulsory.