Eugene Mack was born around 1822 in Ireland to Eugene and Margaret Mack. He eventually immigrated to America, and he probably joined the navy in September 1849. He married Anne Powers on September 23, 1849, and they had at least six children: Annie, born around 1853; Eugene, born around 1855; Frank, born around 1859; Mary, born around 1862; Josephine, born on January 27, 1871; and Marion, born on January 22, 1873.
He served as an ordnance gunner during the Civil War. Navy officials assigned him to the USS Cumberland in October 1860. The Confederate ironclad Virginia sank the Cumberland in March 1862, and he spent the next few months at the New York and Boston Navy Yards. He was assigned to the Mississippi River Squadron in December 1862. Then, in April 1864, he was transferred to the USS Niagara.
He remained in the navy after the war, and he was assigned to the Boston Navy Yard from September 1869 until August 1872. By 1870, his family was living in Somerville, Massachusetts, and he owned $5,000 of real estate and $2,000 of personal property. He served aboard the Ohio from October 1874 until December 1875, and he served at the Boston Navy Yard again from November 1876 to September 1877. Navy officials transferred him to the Portsmouth Navy Yard in October 1877, and he remained there until April 1883. He spent the next few months at the Boston Navy Yard. He died of brain disease in Somerville on July 25, 1883.