Keep her

One woman couldn't make the difference in a war this huge. She could however drastically increase the chance that you wouldn't end up on someone else's cock. Since she was offering to stay anyways it was an easy decision to keep her. Especially with her offer to teach you what she knows. In more ways than one you were looking forward to that

"Then I'll let the LT know you'll be with us. Glad to have you." You said, stripping yourself as you spoke. She gave a smile as she understood your intentions.

"I checked myself before going into battle and I wasn't very fertile. You still might have knocked me up but if you want me on the field past the first month we should probably keep to my mouth until we know." She suggested, helping you undress, giving your cock a few quick strokes as it finally came free. You had to admit she had a point, you would be able to test by next week if your seed had taken so using her mouth until then wouldn't be a major sacrifice. "So how do you want me? On your cock? Your pussy? Both? 69?"