Earl Granville lost his leg while serving in Afghanistan under the Pennsylvania Army National Guard in 2008, WCVB reports. He had competed in marathons before, using a hand bike.
During this year's Boston Marathon, however, he walked. Adding to the powerful imagery, as Granville neared the end, he put his guide over his shoulders.
WCVB posted the video to Facebook, where it has millions of views and has been flooded with positive comments.
"This is what Boston Strong is all about! Great sportsmanship and humanity," wrote one viewer.
"The human spirit is alive and well, what a triumphant moment for these two - and in turn, all of us," wrote another.
In a Facebook post, Granville expressed his gratitude for all the support.