Now she is sharing more of herself than ever before.
In a series she calls her "body image project," Ennis, 25, spotlights her road to recovery as an amputee in a series of striking poses. The last one, shown exclusively to PEOPLE to unveil the final stage of her post-op body, sees her with the prosthetic leg with which she first walked in February.
Courtesy Kirstie Ennis
"Essentially I did it to empower myself," Ennis, who famously shared a hug with fellow Afghanistan veteran Prince Harry, tells PEOPLE of the intensely personal series. "I wanted to show I could be beautiful and strong even without my leg."
Chronicling her changing body before the amputation and then after she underwent a second amputation above the knee shortly before Christmas, it started out as a personal project soon after she returned from the grueling1,000-mile hike in the U.K. that she completed with the Harry-backed charity Walking with the Wounded.
Courtesy Kirstie Ennis
She wasn't expecting to reveal it publicly. (The last shot, like the others by San Diego photographer Marissa Boucher, has been flipped so that her prosthetic left leg is facing the camera.)
"A couple of people reached out to me and said, 'Hey, I have a friend who's had a hard time, would you mind sharing those photos with me?' So I would share them and they'd say, 'You need to show more people these, because they help people from all walks of life,' " says the former U.S. Marine.
Heathcliff O'Malley / WPA Pool / Getty
"I have had other female amputees say, 'These are awesome, you’ve inspired me.' "
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"In today's society, there's this huge wave of body change going on. At the end of the day we are all the same underneath, we just look a little bit different."
Ennis, who has been supported by the Bob Woodruff Foundation, has undergone more than 38 operations since the 2012 helicopter crash that left her severely injured.
The bikini enabled her to reveal those injuries too. "I wanted to show the scars initially, anywhere on my body, even the disfiguring scar on my face," she says. "I wanted to portray the scars but I also I wanted to show the evolution of what I have been through.
"At the end of the day, the struggle of what you go through – whether it be traumatic or if you have a bad day in everyday life – the struggle is what makes you stronger."
She is now a junior director with Wounded Warrior Outdoors, which works to get service people back outside doing various activities. She has set her sights on climbing the Carstensz Pyramid in Indonesia with The Heroes Project. The climb has never been attempted by a woman with injuries like hers.
Ennis recently suffered a complication with her adductor tendon and her femur and is working with specialists to build up the muscle where it meets her prosthetic. But the determined veteran is still on course to take part in a series of events at Prince Harry's upcoming Invictus Games in Orlando beginning May 8.
"I'm trying to move forward without being a sitting duck with my leg," she says, adding: "I can do whatever I want to do – it might just take a little longer and I have to find the means to do it. I am completely able."
"Physically I am different," she says, "but I am just as whole."