The six - captains Philip Bates, 26, Darren Bartlett, 24, and Ian Barlow, 29, Lieutenant Matthew Tupling, 24, and officer cadets Nicholas Oettinger, 20, and Andrew Stout, 20 - had denied raping the woman at the Royal Military College of Science in Shrivenham, Oxfordshire, on 27 May last year.
The jury at Oxford Crown Court had heard that the woman, who cannot be named for legal reasons, claimed the men assaulted her in a bedroom at the college after a drunken day out at a nearby fete. The officers said she had consented to having sex.
The following day the men sent the woman a bunch of flowers with the message "Sorry about the misunderstanding. Please accept apologies from all involved."
During the trial a friend of the victim told the jury that she had twice spoken with her on the telephone in the week leading up to the alleged assault. The friend said she was pestered to join in a group sex session with the woman and a group of Army officers.
The court also heard that 10 days before the alleged attack, the woman had had sex with Oettinger and another man at the college while Bates lay beside them in a drunken stupor.
When the woman reported the alleged rape to police six months later, she failed to mention the earlier group sex session. She also failed to tell police that she had had sex with another of the men, Stout, just hours before the alleged rape.
Judge Julian Hall decided that inconsistencies in her evidence made it unsafe to allow a jury to reach verdicts.
He said the defence's attacks on the woman at the centre of the case were not "attacks on her morals or on her way of life, they are attacks on her credibility or reliability as a witness in this case". He was conscious that it was normally for the jury to decide the facts of the case, but he had acted as a filter in this case to ensure a fair trial. However, he added, "If six men think it's a good idea to have sex with one woman, they run the risk of being accused of rape. I think they have brought this prosecution on themselves."
He said the six realised they had gone too far after the girl was obviously upset - the episode was "almost bound to end in tears". The judge went on: "It was ill thought through by everybody and it does no one any credit."
He ordered that the six men's costs should be paid in full.
A spokeswoman for the Army said: "The Army authorities will now consider what action would be appropriate. Until that consideration is complete we are unable to comment."Reuse content