A second trial took place in September but, after two weeks of evidence and 16 hours of deliberations, the jury was unable to reach a verdict and so was discharged from the service by Judge Claire Ryan.
As she did so, Ward's mother stood up and started crying while the defendant rested his head in his hands.
The woman, who has automatic name suppression, alleged Ward came into her cabin uninvited and forced his way into her bed on a ship following celebrations of the Navy's 70th anniversary.
The woman alleged Ward pinned her down, groped her breasts and digitally penetrated her against her will, only stopping when another person entered the cabin.
Ward's defence was that the encounter was consensual, otherwise he wouldn't have gone as far as he did.
The complainant and Ward were approached for an interview but both declined.
Alysha McClintock, who prosecuted the case, said a decision was made about a further re-trial in this case in accordance with the criteria in the Crown Prosecution Guidelines.
That decision took into account the views of the complainant, she said.
A spokesman for the New Zealand Defence Force said that following the allegations, the chief of Defence Force, Lieutenant General Tim Keating, announced a programme called Operation Respect had been launched.
It is primarily aimed at the prevention of, and appropriate response to, harmful sexual behaviour throughout the NZDF.
The spokesman referred to a press release announcing the programme which said research had revealed "that for some in the Defence Force, the prospect of a formal command investigation in the event of a sexual behaviour issue is/was a barrier to coming forward and accessing help".
It would be up to the victim if they wanted to have the complaint investigated and referred to the police which the NZDF said was a more "victim-centric" approach used successfully by other militaries.
