Prosecutors seeking to justify a lengthy sentence (and the abuses that had already occurred) in the Chelsea Manning case insisted the documents she leaked had caused serious damage to those exposed by them. They said this even as multiple government officials admitted the most the United States had suffered was some embarrassment.
Jason Leopold has obtained an official assessment of the Manning leaks which shows the same thing: no real damage was done.
Regarding the hundreds of thousands of Iraq-related military documents and State Department cables provided by the Army private Chelsea Manning, the report assessed “with high confidence that disclosure of the Iraq data set will have no direct personal impact on current and former U.S. leadership in Iraq.”
This doesn't necessarily mean no damage was done. But the report confirms the United States didn't suffer from the Manning leaks.
The report also determined that a different set of documents that was published the same year, relating to the U.S. war in Afghanistan, would not result in “significant impact” to U.S. operations. It did, however, have the potential to cause “serious damage” to “intelligence sources, informants and the Afghan population” and U.S and NATO intelligence collection efforts.
The report [PDF] also notes investigators located the encrypted Wikileaks "insurance" file -- one Julian Assange says he'll release the key to if he feels his ability to disseminate information is threatened. (Stay tuned!) The assessment concludes it's unlikely this file contains anything damaging either.
Based on public statements by Assange, the IRTF assesses with moderate confidence that the "Insurance File" does not contain any USG data beyond what the IRTF has already reviewed.
The document dates back to 2011. It may have been some use in Manning's defense during the trial (a defense severely limited by the nature of espionage proceedings). As Leopold notes, Manning was not allowed to view this report. Instead, she was forced to fight the charges blind while prosecutors cherry-picked portions of the report to bolster their arguments.
Not that any of this matters at this point. The damage has already been done to Manning's life. And Manning's prosecution likely serves as a low-key chilling effect to dissuade potential leakers and whistleblowers from publicly humiliating the US government. But it does show the government is willing to use evidence that doesn't actually exist to secure a conviction.