The documents number in the hundreds of thousands. They take the form of reports written by soldiers after vicious firefights with insurgents, or after a roadside bomb has gone off, or the bodies of a family have been found murdered in an abandoned factory. Their language is military - hard and attenuated.
We found, with relative ease, reports of horrible abuse committed by Iraqi security forces on detainees - beatings, electrocution, the use of an electric drill on a man's legs. The Americans were aware the abuse had taken place. On some, not all, of these reports was marked "no further investigation", suggesting that American forces took no action on learning of the abuse.
The true lessons contained in these documents will take months or years to emerge. But an early question they pose is: why do Iraqi security forces appear to be continuing practices that might have died with the fall of Saddam Hussein's regime? And what has the United States done to end them?
Julian Assange said the "intimate details" of the conflict were made public in an effort to reveal the truth about the conflict.
The "war logs" suggest evidence of torture was ignored, and detail the deaths of thousands of Iraqi civilians.
The US and UK have criticised the leak, the largest in US military history.
A Pentagon spokesman dismissed the documents as raw observations by tactical units, which were only snapshots of tragic, mundane events. He called their release a "tragedy" which aided enemies of the West.
The UK also condemned the unauthorised release of classified material.
"This can put the lives of UK service personnel and those of our allies at risk and make the job of the Armed Forces in all theatres of operation more difficult and more dangerous," said a Ministry of Defence statement.Casualty of war?
Speaking at a news conference in London, though, Mr Assange defended the release of the documents, saying there were no reports of anyone coming to harm following the release of similar documents on Afghanistan earlier this year.
He said that the snapshots of everyday events offered a glimpse at the "human scale" of the conflict.
Citing a famous refrain that "the first casualty of war is truth", Mr Assange added: "We hope to correct some of the attack on the truth that occurred before the war, during the war and which has continued on since the war officially concluded."
The new documents and new deaths contained within them showed the range and frequency of the "small, relentless tragedies of this war" added Prof John Sloboda of Iraq Body Count, which worked with Wikileaks to analyse the material.
The logs showed there were more than 109,000 violent deaths between 2004 and the end of 2009.
They included 66,081 civilians, 23,984 people classed as "enemy", 15,196 members of the Iraqi security forces, and 3,771 coalition troops.
The figures appear to contradict earlier claims that the US did not keep records of civilians killed.
Iraq Body Count, which collates civilian deaths using cross-checked media reports and other figures such as morgue records, said that based on an analysis of a sample of 860 logs, it estimated that around 15,000 previously unknown civilian deaths would be identified.
Prof Sloboda said the level of detail in the Iraq logs offered new insights into day-to-day events at the height of the conflict.
"Targeted assassinations, drive-by shootings, executions, checkpoint killings; these are the small but relentless tragedies of this war that these logs reveal in unprecedented detail," he said.
Wikileaks - which earlier this year released more than 90,000 documents on the war in Afghanistan - said it was confident that the documents, published in a heavily censored form, contained "no information that could be harmful to any individual".
The 391,831 US army Sigacts (Significant Actions) reports published by Wikileaks on Friday describe the apparent torture of Iraqi detainees by the Iraqi authorities, sometimes using electrocution, electric drills and in some cases even executing detainees, says the BBC's Adam Brookes.
The US military knew of the abuses, the documents suggest, but reports were sent up the chain of command marked "no further investigation", our correspondent adds.
Under a "frago" - or fragmentary order, which changes an existing order - discovery by US staff of "Iraqi on Iraqi abuse" required no further investigation.
The report of one such incident in 2005 - of which the BBC has seen a redacted version - refers to a "frago" that "now requires reports of Iraqi on Iraqi abuse be reported through operational channels".
It continues: "Provided the initial report confirms US forces were not involved in the detainee abuse, no further investigation... (redacted) unless directed by... (redacted)."
One document shows the US military was given a video apparently showing Iraqi Army (IA) officers executing a prisoner in the northern town of Talafar.
"The footage shows the IA soldiers moving the detainee into the street, pushing him to the ground, punching him and shooting him," states the log, which also names at least one of the perpetrators.
In another case, US soldiers suspected army officers of cutting off a detainee's fingers and burning him with acid.
A Pentagon spokesman told the BBC that if abuse by the Iraqi security forces was witnessed, or reports of it were received, US military personnel were instructed to inform their commanders.
The documents also reveal many previously unreported instances in which US forces killed civilians at checkpoints and during operations
In one incident in July 2007, as many as 26 Iraqis were killed by a helicopter, about half of them civilians, according to the log.
Another record shows an Apache helicopter gunship fired on two men believed to have fired mortars at a military base in Baghdad in February 2007, even though they were attempting to surrender. The crew asked a lawyer whether they could accept the surrender, but were told they could not, "and are still valid targets". So they shot them.
A helicopter using the same callsign - Crazyhorse 18 - was also involved in another incident that July, in which two journalists were killed and two children wounded. It is not possible to establish whether the helicopter crew was the same in both incidents.
There are also new indications of Iran's involvement in Iraq, with reports of insurgents being trained and using weapons provided by the Islamic Revolution Guards Corps (IRGC).
Wikileaks has been asked to remove the documents from the web and return them to the Department of Defense, and Mr Assange said that media organisations in the US and elsewhere were coming under pressure from the Obama administration not to report on or publish them.
The investigation into July's Afghan leak has focused on Bradley Manning, a US army intelligence analyst who is in custody and has been charged with providing Wikileaks with a video of the July 2007 attack by a helicopter with the callsign Crazyhorse 18.
The release of the documents comes as the US military prepares to withdraw its 50,000 remaining troops from Iraq by the end of 2011.
Violence in the country has declined sharply over the past two years, but near-daily bombings and shootings continue.