This book was originally published in 1962. It tells the story of the Irish patriot who stole the crown jewels of England and fought against the dictatorship of Oliver Cromwell.
This was one of many paperbacks to be written by Gardner Fox. Fox is best known for the work he did in the comic book industry. He wrote over 4,000 comics and, during his time at DC, he created The Flash, Hawkman, and the Sandman. He was also responsible for creating the Justice Society of America, which was the first “super group.” He also worked in the pulps, writing hundred of paperbacks in all genres.
Unfortunately, the identity of the artist responsible for this cover is unknown.