Both sons became powerful symbols of Saddam Hussein's regime
Only the capture or killing of Saddam Hussein himself could be of greater significance.
His elder son, Uday, and younger son, Qusay, played such legendary roles in Iraq's iron fist rule that their hold over people continued even while they were at large.
There appears to have been a view among ultra-loyal Baathists that, while all three were alive, there was a possibility that things could be made unbearable for the coalition forces and the old regime could return.
However distant that prospect, it was enough to instil among others the fear of terrible retribution.
They had seen it happen when the regime's forces hit back after the uprisings that accompanied the 1991 Gulf War.
While Saddam Hussein remains on the run from the coalition, there could be some Iraqis still unwilling to set those fears aside, or indeed some who would still cling to the notion of his return.
The hunt for Saddam Hussein will no doubt now gain fresh impetus
But the killing of his two all-powerful sons is so symbolic that it can only be hugely disheartening for the arch-loyalists.
And experts suggest it could make reluctant Iraqis more willing to cooperate with the coalition on the ground - even in the efforts to find out whether Iraq did retain or was developing weapons of mass destruction.
Qusay, 36, had become Saddam Hussein's heir apparent.
Control of key areas of the country's security apparatus fell to him.
He was head of Al Amn al-Khas, or the Special Security Organisation, and that put him in charge of concealing any weapons of mass destruction.
Uday, who was 39 years old, became renowned for his instability.
He controlled crucial media outlets.
And he was centrally involved in the illegal international trade that helped keep the regime in power.
But as important as the impact of their deaths on ordinary Iraqis, it is the effect on the coalition forces and on their hopes of stabilising and rebuilding Iraq that is crucial.
It will boost the morale of US troops who have faced almost daily guerrilla-style attacks, even if those attacks do not stop in the immediate future.
The effect on US soldiers will also be crucial
It will give new impetus to the search for Saddam Hussein.
What is not clear at this stage is whether Uday and Qusay had any hand in the attacks on the Americans.
But, the security situation has been so interlocked with the restoring of basic services to the Iraqi population, and with the post-war reconstruction of the country.
So any prospect now of even a reduction in the violence against coalition forces, and against Iraqis working with them, must improve the chances of breaking that vicious circle.
Now that any lingering influence Saddam Hussein was exercising has been dealt this major blow, one of the key questions will be whether it boosts the standing and the potential effectiveness of the Iraqi Governing Council, the body selected by the Americans and installed in Baghdad recently.
Significantly, the United Nations Secretary General, Kofi Annan, has just welcomed it as a first step towards handing the control of Iraq over to the Iraqi people.
The council will be able to choose ministers and the idea is that it will work towards the drawing up of a new constitution and the holding of elections, but final authority for now will rest with the coalition.
Without broad public confidence its task will be immensely harder.
Even if and when Saddam Hussein's fate is finally determined, the council's challenge will be to win that confidence.
The drawing in of Saddam Hussein's inner circle in this dramatic fashion may be a watershed along the way.