The panic that, with devastating consequences, swept through the vast throngs of Shia worshippers in Baghdad yesterday proved more lethal than any terrorist attack. The shouted warning that there was a suicide bomber in their midst may have been given in good faith, although the possibility cannot be ruled out that this was terrorism in yet another guise, a murderous exploitation of the deadly impact that fear can have on closely packed crowds. Pilgrims at Shia religious festivals have frequently been targeted by terrorists, and the crowd’s nerves had been set on edge by mortar attacks in the vicinity of the Kadhimiya mosque earlier in the day.

In the stampede, hundreds were crushed to death and hundreds more jumped, or were pushed, from a bridge spanning the Tigris. The dead, still being counted, could exceed 1,000; inevitably and painfully, the strong trampled the weak in unintended fratricide, with children, women and the elderly coming off worst. The piles of abandoned slippers on the bridge tell their terrible story. More people were killed yesterday than in any other incident since the fall of Saddam Hussein.

This was, said President Jalal Talabani, “a great tragedy which will leave a scar on our souls”. He spoke for all Iraqis, bar the despicable few for whom every Shia death is a victory for the politics of hate that seeks, by fomenting civil war, to destroy their countrymen’s hopes of repairing the fractures of history within a relatively tolerant and pluralist democracy.

As they mourn the dead, as they angrily demand to know what really happened, some Iraqis may be tempted to take the terrorists’ poisonous bait; but the great majority understands that civil war is at all costs to be avoided. They are entitled to demand more maturity from their political leaders than was shown yesterday by the Iraqi health minister. In this terrible emergency, he must surely have had more urgent things to do than to heap blame on the interior and defence ministers and to call for their resignations. The politicians elected last January took an unconscionable time to form a government and have yet to prove that they can function as an effective team that delivers — in appallingly difficult circumstances — desperately needed basic services. More than ever, they need to show that, spurred by this terrible event, they can pull together — not only for the immediate relief of suffering, but in reaching whatever further compromises are needed to win endorsement of the constitution by all Iraq’s communities, including a sufficient number of Sunnis, in the referendum to be held next month.

There is enough ambiguity in some passages of the draft presented last Sunday to the Iraqi Parliament to allow for “editing” adjustments designed to reassure the minority Sunnis that they would, at the least, be assured both of a proper voice in national affairs, and of their fair share of oil revenues under a constitution that will devolve substantial powers to the regions. Zalmay Khalilzad, the US Ambassador to Iraq, hinted yesterday the Iraqis “amongst themselves” could find ways to adjust the text, without appearing to reopen negotiations. The US cannot be seen to do more than encourage. But human tragedies can be catalysts that tame bitter antagonisms, as the tsunami appears to have done in the Indonesian province of Aceh. From the horror in Baghdad, a better Iraqi future could yet be born.