Where are the U.S. POWs? Where are the chemical, biological or nuclear weapons? How extensive were Iraq's ties to terrorists?
As the Iraqi regime crumbles, much more remains unknown than Saddam Hussein's fate. Even as the battles continue, coalition forces are seeking answers to these questions.
One grisly clue appeared -- blood stains and bullet holes on uniforms found at an Iraqi prison, believed to be of recent American prisoners of war.
"They were U.S. uniforms. And there were names on some," said Brig. Gen. Vincent Brooks, deputy director of operations. But where the POWs are is still unknown, he said.
Barrels found at an agricultural site south of Baghdad -- where preliminary tests indicated the possibility of chemical weapons -- have been sent for thorough tests.
Questions about terrorist links to Saddam's regime have yet to be nailed down. Troops, however, braced for the possibility of more suicide attacks while the military seeks to consolidate control over cities with sporadic resistance.
And a big battlefield question is also worrying U.S. military and administration officials: What happened to Saddam's troops? A U.S. official involved in both military operations and intelligence said there are thousands of Iraqi troops unaccounted for -- raising ominous questions.
"That's the scary part," said the official, who spoke on condition of anonymity. "We don't know where these guys went to. Did they just melt into the population? Are they planning to come back out as paramilitary? Are they laying in wait?"'
Some slowly and some quickly, the answers are coming, said analysts and retired military. "Some of this can take weeks or months to sort out, depending how well the regime concealed it," said Anthony Cordesman, a military analyst at the Center for Strategic and International Studies.
"You have access to the records and access to the people," he said. "Whatever is there, sooner or later is going to come out."
Not that the military was taking its time.
Defense Secretary Donald H. Rumsfeld on Wednesday announced unspecified rewards for Iraqis who provide information about government officials and weapons of mass destruction.
"Rewards are available to those who help us prevent the disappearance of personnel, documentation and materials," he said at a Pentagon news conference.
The challenges are proliferating rapidly: the need for order amid looting and lawlessness, the threat of would-be suicide attackers, the first steps toward civilian government.
Solving the most immediate problems is more urgent than terrorist links or the search for weapons of mass destruction, though they can't be ignored, said Harlan Ullman, a military strategist who taught at the National Defense University.
"Now the issue becomes waging the peace," Ullman said. "As we wind the war down, as we mop up opposition, as we put in law and order, we're going to need to roll in additional capabilities to deal with the peace."
Establishing order will help answer many of the other questions, said Frederick Hitz, a former CIA inspector general and now a Princeton professor.
"There will be some opportunities here to really fill in the blanks," he said. "There's an opportunity to talk to a whole range of people in Iraq who felt they couldn't talk, up until this moment."
And that could turn up other, potentially explosive answers, said Cordesman: banks that serviced the regime and companies that supplied it with materials and arms.
But the task isn't getting easier quickly. Even as Baghdad streets filled with jubilant crowds, an Army unit near the Ministry of Information came under fire from rocket-propelled grenades.
Beyond those daily challenges are larger questions -- the war's effect on the Middle East, on U.S. allies in Europe and beyond; warnings of widespread terrorist backlash; the proliferation of weapons of mass destruction that was the argument at the heart of the conflict itself.
"It is not an easy path we go down now," said retired Maj. Gen. William Nash, who commanded NATO-led peacekeeping forces in Bosnia during the first year after the civil war ended in 1995.
"While today was certainly a great day in the whole effort to free the Iraqi people and defeat Saddam's regime, there's a lot of work ahead," he said.
The search for Saddam himself continued, as did the search for the POWs.
Brooks at U.S. Central Command issued a warning: "We hold the regime, whatever remains of it or whoever might have our prisoners of war in possession, accountable and responsible for anything that happens to them."