The attackers were roughly forty members of the Movimiento Todos por la Patria, or MTP, "All for the Fatherland," led by Enrique Gorriarán Merlo, a veteran of the older guerrilla group ERP. Their stated reason was alarming and plausible: the Carapintadas, mutinous army officers who had rebelled three times in 1987 and 1988 against trials for the dictatorship's crimes, were said to be plotting another coup, and the MTP claimed it was defending the constitution by striking first. Other accounts, including the army's, insisted the militants were the ones plotting insurrection, hoping to seize the base and spark a popular revolt. The truth remains contested. What is certain is that they brought the war back to a country that had laid it down.

The assault collapsed almost immediately into a siege. The army and the Buenos Aires police, some 3,600 personnel in all, surrounded the base and fought to retake it. In the course of the battle, soldiers used white phosphorus inside the compound, a weapon whose use in this way is barred under international law; it set the barracks ablaze and left bodies charred beyond recognition. When the smoke cleared, nine soldiers, two police officers, and twenty-eight MTP members were dead, most killed by conventional weapons. Among the militant dead was the lawyer Jorge Baños, who only days earlier had stood at a press conference warning of the coup the MTP said it was trying to stop.

The grimmest questions concern those who were not killed in the fighting at all. Survivors and one former sergeant later testified that prisoners taken alive were tortured, and that at least two captured militants, Iván Ruiz and José Díaz, were last seen in army custody and then vanished, joining the ranks of Argentina's desaparecidos in a democracy that had vowed never again. A conscript claimed that a soldier, adjutant sergeant Esquivel, was shot by his own side while trying to reach a captured brother. The dead of La Tablada do not divide cleanly into heroes and villains. They divide instead into the human and the missing, and into families on every side who were left to bury people, or worse, to keep asking where they went.

Twenty surviving MTP members were tried under a hastily passed law that denied them the right of appeal, and given sentences from ten years to life; Gorriarán Merlo received life. The convictions sat uneasily even with critics of the attack, because a democracy that suspends due process to punish its enemies has borrowed something from the regime it replaced. Over the years the sentences were commuted. Gorriarán Merlo was freed in 2003 after fourteen years in maximum security, calling his release "an act of justice," and he died three years later. La Tablada closed the era of armed revolution in Argentina, but it left behind a harder question about how even a free country answers violence without becoming violent itself.