Here is an article about the trial of a dirtbag drill sergeant that was sentenced to 20 years in prison for forcing trainees to have sex with him. What I found of interest is another example of why these cases are hard to prosecute:

military sexual assault

A medic Sanchez deployed with to Afghanistan accused Sanchez of forcing her to have sex with him while they waited to get evacuated from a combat outpost.
She testified that she didn’t fight back and didn’t report the incident until months later, when she faced repercussions for assaulting a military policeman while drunk in Alaska where she was based.
She mentioned three other men in the military who had assaulted her, but those claims didn’t result in charges. She said the relationship with those men had been consensual at one point.
Pressed for more details about the alleged incident involving Sanchez, the woman testified that she had memory loss from being exposed to three roadside bombs.
“I don’t remember step by step” of how it happened, she told Judge Nance from the stand. (Stars and Stripes)

It is a good thing the prosecution had plenty of other witnesses because if this soldier was the star witness he probably would have gotten off.