Civil War Union Officer, Indian Fighter. He was commissioned by a board of military officers in Washington D.C. as a second lieutenant in the United State Infantry's Fourth Regiment at the age of 20. He served in the Florida Seminole Indian campaigns from 1841 to 1842. After bringing hostilities to a successful end in the region, he was promoted to brigade major in 1845. He fought in the American-Mexican War beginning in 1846 alongside future US President Ulysses S. Grant, successfully defeating Mexican forces in a series of battles for control of San Antonio, El Molino del Rey, and the subsequent capture of Mexico City. Following the successful conclusion of the war against Mexico, he was promoted to the rank of captain of the Fourth Infantry, serving briefly in California and Arizona. In 1852 he was transferred to the Oregon Territory to counter Indian hostilities along the present day Washington-Oregon border. Four years later he received orders to establish and command a garrison fort along the Strait of Juan de Fuca for the protection of white settlers. At the outbreak of hostilities between the North and South he was assigned to the command of General George B. McClellan, in charge of defending the south-central region of Pennsylvania against advancing rebel forces attempting to cross the Susquehanna River. Following the Gettysburg Campaign he was dismissed from the United States Army in 1863 after unproven allegations of disloyalty made by a US Naval officer, claiming that Haller had made disparaging remarks against the Union, and about President Abraham Lincoln's handling of the Battle of Fredericksburg, which resulted in significant loss of life. He was reinstated to the Army in 1873 following a court of inquiry which exonerated him from all charges, and was promoted to the rank of colonel by President Rutherford B. Hayes. In 1880 he was assigned as commander of the 23rd Infantry stationed in Oklahoma, before finishing out his military career in Kansas and New Mexico. Following his military service he moved to Seattle, Washington where he retired as a successful businessman.