In a speech seen as a decisive moment for a president whose approval ratings are languishing in the 40% range, Mr Bush claimed he had a clear plan for the transfer of power to Iraqis on June 30, and asked Americans to stay the course.
"We will not fail. We will persevere, and we will hold this hard-won ground for the realm of liberty," he said.
Last night's address to the Army War College marks Mr Bush's most detailed outline for what will take place in Iraq five weeks from now: the transfer of power to an Iraqi government appointed by the UN; a US-led protection force for Iraq, supplemented by Iraqi troops; and the holding of elections about six months from now.
Earlier yesterday, the administration moved to gain international approval for its plan, presenting a joint US-British resolution to the UN.
But the substance of Mr Bush's plan was still woefully thin, and was seen largely as a concerted effort by Mr Bush to re-engage American public opinion, and stop the erosion in support for his administration.
Aides have said he plans five more such addresses, one each week in the five weeks remaining until the June 30 handover date.
Although Mr Bush tried last night to keep American attentions focused on the future - and away from the prison scandal and a death toll among US soldiers in Iraq that is rapidly approaching the 800 mark - he acknowledged that the coming five weeks are likely to bring an eruption of violence.
"There is likely to be more violence before the transfer of sovereignty - and after the transfer of sovereignty," he said.
The president's speech was the second effort of the day to persuade Americans and the international community that the occupation of Iraq is at an end.
Earlier, at the UN, the US and Britain's resolution called for a caretaker administration - unelected and appointed by the UN - to take office by June 30. "The interim government of Iraq will assume the responsibility and authority for governing a sovereign Iraq," it says.
The resolution also authorises a US-led military force to stay in Iraq for at least a year. There is no clear timetable for the troops to leave, but the resolution mentions that the troops, in theory, could be sent home by the authority installed once elections are held in Iraq.
Tony Blair will today hail the resolution as a highly significant step which gives the lie to anti-war campaigners who claim that British and American forces will remain in Iraq against the wishes of the new government. The resolution makes clear that Iraq's new sovereign government must give its "consent" to troops, he will point out.
Early reaction to the draft was cautiously optimistic, with Germany's UN ambassador describing it as "a good basis for discussion".
Last night, Mr Bush outlined his strategy for Iraq in a much-awaited speech. The prison abuse scandal and increasingly heavy casualties among US forces have driven his approval ratings to the lowest of his presidency, jeopardising his prospects in next November's elections.
He was also facing fresh criticism from a former commander of US forces in the Middle East, Anthony Zinni, who says in a new book called Battle Ready that the Pentagon's civilian leadership betrayed "at a minimum, true dereliction, negligence and irresponsibility, at worse, lying, incompetence and corruption" in the run-up to the war.
In his speech Mr Bush said: "America's task in Iraq is not only to defeat an enemy, it is to give strength to a friend, a free, representative government that serves its people and fights on their behalf. And the sooner this goal is achieved, the sooner our job will be done."
Under the UN resolution unveiled yesterday, the interim structure will take power until elections for a transitional national assembly are held by the end of next January.
The transitional authority will draft a constitution. It will inherit the remaining development funds held by the Coalition Provisional Authority, and will have control over oil revenues. However, an international board would audit spending of oil proceeds for at least the next 12 months.
It was unclear how much control the new Iraqi government will have over the US-led military force, or who would take over the detention centres and some 8,000 Iraqi prisoners now under the control of the US military.
The resolution gives the US-led force "the authority to take all necessary measures to contribute to the maintenance of security and stability in Iraq including by preventing and deterring terrorism".
The US deputy ambassador to the UN, James Cunningham, told reporters yesterday that questions of control over the forces would be dealt with in an exchange of letters between Washington and the new government.
That sits uneasily with France and Germany, with Berlin proposing the creation of an Iraqi national council to give Iraqis a say in their own security.