Frank O’Brien was born in 1892 in Fargo. At 18, he began working at the Fargo Mercantile Company, a wholesale grocer. Like many young men of his time, Frank was drafted after the United States declared war on Germany in 1917. He was among the first draftees from Fargo and was inducted in September 1917. After arriving at Camp Dodge, Iowa, Frank wrote a letter to his former colleagues at the Fargo Mercantile Company, describing his training as a member of an infantry supply company.