A British photographer set out on a nearly impossible task in 2005 – to capture the faces of the last living veterans of World War I. 

In a series titled "The Old Guard," U.K.-based photographer Giles Price displays Britain's last remaining WWI veterans, many of whom were well over 100 years old by the time they sat down for their portrait. According to Slate, when Price came up with the idea to track down the veterans, only 23 of the roughly 9 million British military members who served in WWI were living. 

"I was aware that very few were still alive and wanted to document them while they were alive," Price told the news source. "I was 20 minutes from taking one sitter when the home rang me to say he had passed that morning. He was 106."

Price traveled to each veteran's home to take their photo. A Royal Marines veteran who fought in Iraq in the early 1990s, Price added that being a former military member influenced the way he shot and edited his subjects, some of whom chose to wear their service medals for the photo shoot.

The New York Times reported in 2012 that the last known World War I veteran on either side of the conflict, Florence Green, passed away at age 110.