Harrie Irving Hancock (H. Irving Hancock) was born January 16, 1868 in Massachusetts. Hancock was a prolific writer, an American chemist, and a Jiu-Jitsu expert. He is mostly known for his juvenile "boys" series such as The Grammar School Boys/Dick & Co. Series, The High School Boys Series, The Young Engineer Series, and Uncle Sam's Boys Series, but was also well-known for his physical fitness writing which included several manuals on Jiu-Jitsu. Hancock was also a war correspondent, which lead to his historical fiction series on a German invasion of the United States. Hancock married Nellie Stein on December 21, 1887 and had two adopted daughters. Hancock died of liver illness in Blue… Point, Suffolk County, New York on March 12, 1922.