As a ranking officer battles to keep himself and his comrades alive and sane in the final months of the great war, a chance encounter with his lost love finally brings the truth of why she disappeared with their baby girl a decade ago and inspires him to try and rekindle the life together that was so prematurely taken from them.

K.I.S.S.= Keep It Simple Stupid. The logline is not only too long, but it is also too complicated.

Thanks for your comments, I'm afraid i don't know the rule of K.I.S.S Please would you explain it to me?
Also when you write weakness, is that in regards to the description of the character? Thanks

I agree with Tor's suggestions for streamlining the idea down to it's most basic components.

I feel like I want some more specificity in the logline. A chance encounter as your inciting incident, and the goal being to rekindle their romance, both feel too vague. What are the circumstances of the encounter? What specifically is the protagonist trying to do to re-build their life together?

With that in mind, I'm not clear how the fact that it's all happening during a war factors into it? What country is he fighting with? Is he stationed in the same city as where he used to live? Or is his lost sweetheart now somewhere where he could bump into her? I'm too confused at this stage to say I think the logline is working as tight as can be.