Myron H. Cook was born around 1843 in Illinois to Moses Cook and Hannah Pixley. His father was a farmer who owned $4,000 of real estate and $1,000 of personal property by 1860. Cook grew up and attended school in Crete, Illinois. He enlisted in the Union army on August 11, 1862, and he mustered in as a private in Company F of the 8th Illinois Cavalry alongside his brother Joseph the following day. According to his service records, he was 5 feet, 6 inches tall, with brown hair and gray eyes. The regiment took part in the Battle of Antietam and the Battle of Fredericksburg. He died near Stafford Court House, Virginia, on March 20, 1863.