NAJAF, Iraq, Aug. 17 - Just five days after they arrived here to take over from Army units that had encircled Najaf since an earlier confrontation in the spring, new Marine commanders decided to smash guerrillas loyal to the rebel Shiite cleric Moktada al-Sadr.
Acting without the approval of the Pentagon or senior Iraqi officials, the Marine officers said in recent interviews, they turned a firefight with Mr. Sadr's forces on Thursday, Aug. 5, into a eight-day pitched battle, one fought out in deadly skirmishes in an ancient cemetery that brought them within rifle shot of the Imam Ali Mosque, Shiite Islam's holiest shrine. Eventually, fresh Army units arrived from Baghdad and took over Marine positions near the mosque, but by then the politics of war had taken over and the American force had lost the opportunity to storm Mr. Sadr's fighters around the mosque.
Fighting here continues, and what the Marines had hoped would be a quick, decisive action has bogged down into a grinding battle that appears to have strengthened the hand of Mr. Sadr, whose stature rises each time he survives a confrontation with the American military. It may have weakened the credibility of the interim Iraqi government of Prime Minister Ayad Allawi, showing him, many Iraqis say, to be alternately rash and indecisive, as well as ultimately beholden to American overrule on crucial military and political matters.
As a reconstruction of the battle in Najaf shows, the sequence of events was strikingly reminiscent of the battle of Falluja in April. In both cases, newly arrived Marine units immediately confronted guerrillas in firefights that quickly escalated. And in both cases, the American military failed to achieve its strategic goals, pulling back after the political costs of the confrontation rose. Falluja is now essentially off-limits to American ground troops and has become a haven for Sunni Muslim insurgents and terrorists menacing Baghdad, American commanders say.
The Najaf battle has also raised fresh questions about an age-old rivalry within the American military - between the no-holds-barred, press-ahead culture of the Marines and the slower, more reserved and often more politically cautious approach of the Army. Army-Marine tensions also have surfaced previously, notably when the Marines opened the Falluja offensive.
As they replay the first days of the Najaf battle, some commanders are wondering if a more carefully planned mission would have had a better chance to succeed.
"Setting conditions for an attack requires extensive planning and preparations," said Lt. Col. Myles Miyamasu, who commands an Army battalion that arrived to reinforce the Marine unit here two days after the fight began. "If you don't have those things in place and you attack, a lot of times it fails."
When the United States transferred power to the interim government in June, both American and Iraqi officials insisted that authority for major decisions on the use of force would be exercised by the new Iraqi leadership, in particular Dr. Allawi, a former enforcer for Saddam Hussein's Baath Party who defected in the 1980's and became leader of an exile political party. Senior United States military commanders emphasized that while they retained command of their troops, the forces were there to serve the Iraqi government.
But in the battle in Najaf, at least, the marines here say they engaged Mr. Sadr's forces at the request of the local Iraqi police. They did not seek approval from senior military commanders or from Iraqi political leaders, with the exception of the governor of Najaf. The governor, Adnan al-Zurfi, an Allawi appointee, refuses to confirm having given the green light, although American commanders in Baghdad cited his commands repeatedly as the political cover for the Marine attack.
In past week, the interim government has twice halted major American-led attacks on Mr. Sadr's forces as they were about to begin. It now says it will use Iraqi troops for future battles. But it is far from clear, judging from the lukewarm assessments of American commanders in Najaf, that the American-trained Iraqi units that fought alongside the Americans last week are capable of taking the lead in any showdown with Mr. Sadr.
The seeds of the Najaf battle were sown on July 31, when the 11th Marine Expeditionary Unit, commanded by Col. Anthony M. Haslam, replaced units of the Army's First Armored Division and First Infantry Division, which had fought Mr. Sadr's militiamen for weeks in the spring before a series of truces around Najaf. The marines began to skirmish with the Iraqi fighters almost as soon as they took responsibility for this holy city of 500,000, American officers and Mr. Sadr's militiamen say.
Senior officers in Baghdad, as well White House officials who discussed the battle in Washington, say the latest fighting began when a Marine patrol drove directly past one of Mr. Sadr's houses in Najaf - violating an informal agreement that American units would stay away from Mr. Sadr's strongholds, treating them as part of an "exclusion zone" that was at the heart of the cease-fire in the city.
Two days later, on Aug. 5, fighters in Mr. Sadr's Mahdi Army staged a 2 a.m. attack on a police station in Najaf. Usually, the police are an easy mark, but this time, the White House official said, "they shot back" and called for American reinforcements. When the militiamen pushed forward a third time, about 7 a.m., American commanders in Baghdad said, the governor, Mr. Zurfi, called for American reinforcements.
American intelligence officials monitoring Mr. Sadr said he then summoned reinforcements from around the country, and Ambassador John D. Negroponte, the top American official in Iraq, "decided to pursue the case," one official said. One result was a domino effect, with the fighting in Najaf soon replicated in more than half a dozen cities and towns across southern Iraq that are Mahdi Army strongholds, including the Baghdad slum of Sadr City, Diwaniya, Kut, Al Hayy, Nasiriya, Amara and Basra.
The battle in Najaf quickly centered on a huge cemetery adjacent to the Imam Ali Shrine, which had been off limits to American troops as part of a truce worked out after earlier fighting in April. At its closest point, the L-shaped cemetery, more than five square miles of tombs and catafalques and crypts, is only a few hundred yards from the shrine. Marine commanders in Najaf acknowledge that they did little planning for the battle, but say they gambled that they could reach the walls of the Old City so fast that they would outrun the political firestorm sure to result.
"We just did it," said Maj. David Holahan, second in command of the Marine unit in Najaf.
Inside the cemetery, the battle was exceptionally fierce, marines said. Mr. Sadr's guerrillas had secreted away many weapons caches and explosive devices, and as the marines forced their way forward, they traded shots - and hand grenades - with insurgents who were sometimes only a few yards away.
The ferocity of the rebel resistance surprised the marines, who had seen Saddam Hussein's army disintegrate last year as they marched north to Baghdad. "The ones we fought the other day are a hell of a lot more determined," Lt. Scott Cuomo said.
By early evening on Aug. 5, the battalion had sent out an urgent request for reinforcements. Senior commanders sent the First Battalion of the Fifth Cavalry Regiment, a heavy Army unit, from Baghdad.
Maj. Gen. Peter Chiarelli, the First Cavalry Division commander overseeing American troops in Baghdad, said during a visit to an American base in Najaf on Sunday, Aug. 15, that the division did not know until the last minute that the 1,800 marines in Najaf might need reinforcements. The Fifth Cavalry Regiment's tanks and other armored vehicles were patrolling in Baghdad when the request for help arrived, he said. By then, American troops in the capital were under intense pressure themselves, fighting Sadr militiamen in Sadr City and in skirmishes in other Shiite districts.
Army units began to prepare to move immediately, but the 120-mile drive from Baghdad, through some of the most rebel-infested territory in Iraq, took two days, Colonel Miyamasu said, with the forces arriving in Najaf on Saturday. By then, many marines had been fighting for almost 48 hours straight, in temperatures that topped 120 degrees each day.
Still, they had managed to press forward to the west and south, reaching the southern edge of the cemetery, just a few hundred yards from the mosque. But with the Army battalion unprepared to fight Saturday, the marines decided to retreat.
The next day, Aug. 8, the Army re-entered the cemetery. But by then, with political pressures building in Iraq and across the Muslim world, American forces faced immense pressure not to damage the Imam Ali Mosque. The Army never tried to reach the south wall of the Old City, and soldiers fighting inside the graveyard needed permission to fire heavier weapons in the direction of the mosque. The fight became a stalemate.
"If we had arrived one day earlier or the marines had attacked one day later, I'm not sure we'd be in this position," Colonel Miyamasu said.
In Baghdad, commanders seemed curiously disconnected. On Monday, Aug. 9, a senior military official told reporters that American forces had cut off Mr. Sadr's forces in the Old City and the cemetery from the rest of Najaf. But no cordon existed, and none would be set up until Thursday, when the second Army battalion arrived.
Marine officers have said they killed several hundred guerrillas, weakening Mr. Sadr's forces for future fighting, at a relatively low cost in American casualties - 8 marines and soldiers killed and about 30 wounded.
"We put a major hurt on his hard-core militia members,'' Major Holahan said. "Things happened pretty well from a military point of view."
Mr. Sadr's spokesmen have disputed the American figures for their dead, saying fewer than 30 were killed.
On Friday, the Iraqi government and Mr. Sadr's forces reached a tentative cease-fire. Although negotiations with an Allawi government delegation from Baghdad quickly collapsed, amid new threats from Dr. Allawi and his aides of a resumed push on the mosque, Mr. Sadr appeared to have once again withstood American threats and firepower.
Iraqi officials have said the new plan is to use Iraqi units to force Mr. Sadr from the mosque, while assuring fellow Muslims, in interviews broadcast across the Arab world, that they will allow no damage to the shrine.
"I am disappointed," Colonel Miyamasu said Friday, after the cease-fire was announced. "A target of opportunity has passed." But he said American forces would continue to press Mr. Sadr as long as the Iraqi government wanted.
"It's not over," he said. "It's just going to be different."
Alex Berenson reported from Najaf for this article and John F. Burns from Baghdad.