Artist's description from DA:WHO WANTS SOME MANE SIX HEADCANONS??? I KNOW I DO!!!
Anyway all of the following Mane Six updates (excluding Twilight who does not fit into these categories) will showcase the element as a soldier in the First Great War as well as two to three years after the war ended.
Behold the mighty athlete horse. Rainbow Dash.
Despite her pleading to the stars to be placed in the Aeroforce regiment that the Wonderbolts were in when the draft rolled through, she was put into a regular old joe regiment. She was thoroughly disappointed and peeved when she arrived at Basic Training. Needless to say during her training she had the cocky show-off kicked out of her. Sure, she was in a regiment with a hodge podge of slow pokes, but they all seemed tougher than she was. None of them complained as much as she did and on land, they promptly fed her their dust. She had to cut the crap, stop making excuses, and pick up the pace. She got the hang of it pretty quickly after that. RD was primarily trained in gunslinging and weather assault but she dabbled in explosives and bombing a little. She was lucky and made it through the war with just a few cuts and bruises. There was a small incident with an enemy rocket launcher that partially deafened her for a while. She's ok now, she just has a harder time hearing in her right ear.
Later on after the war RD finds a job that she grows a passion for. Once she starts up a family she no longer has the desire to join the Wonderbolts. Instead she goes to work for the Cloudsdale University as an instructor of Aerodynamics and Flight Maneuvers. She's not a tenured professor but she is a kick ass adjunct.