Buchanan joined the Navy from his birthplace of Philadelphia in October 1878, serving until the age of 21.

On that day, while Saratoga was anchored off Battery Park in New York Harbor, Apprentice Robert Lee Robey fell overboard and was swept away by a strong tidal current.

Another sailor, Apprentice John Hayden witnessed the event and, when it seemed that Buchanan needed assistance, he too jumped overboard and helped keep Robey afloat until all three men were picked up by the ship's boat.

For this action, both Buchanan and Hayden were awarded the Medal of Honor a week later, on July 22.

On the morning of this date, Robert Lee Robey, apprentice, fell overboard from the after part of the ship into the tide which was running strong ebb at the time and, not being an expert swimmer, was in danger of drowning.