Henry Leo Abbott was also known as Harry L. Abbott, Henry L. Abbott and Harry Abbott. On his WWII draft registration card, Harry listed himself as Harry L. Abbott.

By 1917 and 1918 when the World War I civilian draft registrations took place, patriotic sprit was running very high in America. As a result, about 98% of adult men under age 46 living in the U.S. in completed registration cards. During those two years, three registration days were held and approximately 24 million men born between 1873 and 1900 completed draft registration cards. Harry's card indicates that he registered on September 12, 1918, which was the last of the three registrations events.

At the time he registered, Harry (Henry) was employed as the business manager for the Theatrical Protective Union, Local #1, in New York City. The registration card indicates that his "nearest relative" was Margaret Abbott, to whom he was married.