It was 21 May 2012, the day before Unity Day, Yemen's annual celebration of the 1990 merger of North and South Yemen. Hundreds of soldiers had gathered at al-Sabeen Square - a ten-lane boulevard near the Presidential Palace and the al-Saleh Mosque, closed to traffic for twenty-four hours before the event. Security had been elaborate. Soldiers were inspected at their bases, transported in military vehicles, and marched through a sealed parade ground. The target of the attack was Defense Minister Mohammed Nasser Ahmed, who would have addressed the troops moments after the national anthem. But the bomber did not wait for the speech. He detonated during the anthem itself, at approximately 10 a.m., positioned perfectly within a unit of his brothers marching in formation.

One soldier who survived reported seeing bodies of soldiers flying through the air. The description is not metaphorical. An explosive belt loaded with thirteen thousand pieces of metal, detonated in the middle of densely packed men in formation, kills indiscriminately in every direction. Local paramedics dispatched dozens of ambulances. Seven hospitals across Sanaa received casualties, some ambulances carrying six or seven wounded at a time. Initial reports counted 63 dead; the final figure climbed to 96 as men died of their wounds in the days that followed. The UN Security Council and the US State Department both settled on 96. Every one of them was a Yemeni soldier, most of them young men from poor families for whom military service was one of the few reliable jobs available.

Ansar al-Sharia, the local affiliate of al-Qaeda in the Arabian Peninsula, emailed Reuters to claim responsibility almost immediately. The timing was significant. Ten days earlier, Yemen's new president Abdrabbuh Mansur Hadi - who had taken office after the February 2012 resignation of longtime dictator Ali Abdullah Saleh - had launched a US-backed military offensive against Ansar al-Sharia positions in Abyan Governorate. By the time of the bombing, AFP tallied nearly 150 Ansar al-Sharia fighters killed in that offensive. A week before the bombing, al-Qaeda leader Ayman al-Zawahiri had released a video calling Hadi a US agent and a traitor. The bombing was revenge, delivered at the heart of the capital, using a recruited soldier to do the killing.

The parade was held the following day, on schedule, at a secret location in the Sanaa air force academy. Presidents and prime ministers around the world had condensed their usual statements of condolence into the same small handful of adjectives - cowardly, despicable, barbaric - as if the vocabulary of international response had no other words available. John Brennan, President Obama's homeland security adviser, called President Hadi; UK ministers issued condemnations; François Hollande, only weeks into his French presidency, expressed solidarity. Russia's Vladimir Putin called it a barbaric crime. The soldiers who had survived the previous morning buried their dead and began the funeral cycle that would continue through the week.

The bombing did not stop the war; it intensified it. Yemeni authorities arrested Majed al-Qulaisi, an AQAP cell member, on 20 June. On 29 June, they apprehended a reported ten-man network accused of facilitating the attack, along with recovering the last testament of the bomber himself - the young soldier whose name is not recorded in most accounts, and whose family's grief was filed away beneath the political significance of his act. On 11 July, an AQAP suicide bomber killed ten more at a police academy in Sanaa. On 11 September, AQAP tried to assassinate the same defense minister again, this time with a car bomb; he survived, seven of his bodyguards and five civilians did not. The New York Times noted that the bombing would likely weaken the morale of Yemeni security forces, already suffering from poor pay, ill treatment, insufficient training, and corruption.

The ninety-six soldiers of al-Sabeen Square were not high officials or symbolic figures. They were conscripts and enlisted men, many of them from the rural hinterlands of a country whose economy offered few alternatives to military service. They had rehearsed a parade that was meant to celebrate unity, a word that by 2012 had lost most of its meaning in Yemen - the country was two years from a full civil war that would kill far more of them. What was left of their names and faces went to families who grieved in homes their sons had been trying, with their salaries, to help support. The men who ordered the bombing were not in the square. The man who carried it out was. He was one of them, which is perhaps what made the attack hardest to absorb.