Julius J. Brown was born around 1833 in New York. He eventually moved to Yorktown, Illinois, and he earned a living as a farmer.
He enlisted in the Union army on September 7, 1861, and he mustered in as a private in Company B of the 34th Illinois Infantry. According to his service records, he was 5 feet, 10 ½ inches tall, with brown hair and blue eyes. The regiment took part in the Battle of Shiloh, the Battle of Perryville, the Battle of Stones River, the Battle of Missionary Ridge, and the Atlanta campaign. He mustered out on September 12, 1864.
He applied for a pension in May 1880 and eventually received one. He died sometime after May 1880.