Not fasting in Ramadhaan due to military duties

I am a soldier and Ramadhaan has arrived, so is it permissible for me to refrain from fasting, bearing in mind that my [military] duties do not help me when I’m fasting (i.e. he experiences much hardship)?

Saw yellow discharge whilst fasting

I have a maternal aunt (mother’s sister) who purified herself [from the completion of her menses] before the Fajr time in Ramadhaan and so fasted that day. She later stood to do her Zhuhr prayer and saw yellow discharge, so is her fast [for that day] valid?