Alexander Peter Whitmer was born at his parent's farm at Far West, Missouri, shortly after their return to Far West, Missouri,. John's family had been banished by leaders of the Latter Day Saints in 1838. John returned in 1839 with his family after the church was expelled from the state of Missouri. Alexander may be named after Alexander Doniphan, a friend of the Saints. Alexander as required to report for duty during the Civil War into the Enrolled Missouri Militia in 1862. He later volunteered for the Federal army in 1864. Soon thereafter, he was killed during a Battle in Tennessee. Alexander's birth date is given in the John Whitmer Family Bible, LDS Church History Library.