Elisha Willard Warren was born around 1843 in Pennsylvania to Elisha Warren and Sarah Lauretta Willard. His father worked as a paper manufacturer. The family lived in East Fallowfield, Pennsylvania, until the 1850s, when they moved to Philadelphia, Pennsylvania. By the early 1860s, he was working as a paper maker.
He enlisted in the Union army on August 1, 1861, and he mustered in as a private in Company C of the 3rd Pennsylvania Cavalry later that day. According to his service records, he was 5 feet, 7½ inches tall, with light hair and blue eyes. The regiment took part in the Battle of Antietam, the Battle of Fredericksburg, the Battle of Gettysburg, and the siege of Petersburg. Warren earned a series of promotions: to sergeant, then to 2nd lieutenant on September 13, 1862, and finally to 1st lieutenant on May 21, 1863. He mustered out on August 24, 1864.
He married Sophronia Stewart on January 4, 1863, and they had at least five children: Mary, born around 1866; Ella, born around 1869; Alice, born around 1874; Frederika, born around 1875; and Estelle, born around 1880. They moved to Artesia, Illinois, after the war, and Warren worked as a farmer. By 1870, he owned $6,000 of real estate and $1,300 of personal property. They moved to Buckley, Illinois, in the 1870s, and Warren and his wife earned a living as schoolteachers there.
They returned to Philadelphia in the late 1800s, and by 1900, Warren was working as a stock broker. He was confirmed in St. Philip’s Protestant Episcopal Church on February 3, 1901. He applied for a federal pension in March 1907 and eventually secured one. He died in Ocean City, New Jersey, on May 22, 1908.