He came to Colorado during the gold rush and arrived on June 27, 1859. When Moore first came to the present-day area of Denver, there were a few cabins in Cherry Creek village, or Denver, and Auraria settlements. The town of Highland was also established. People traveled by wagon train to reach the area. Within a year, the settlements grew and overland coaches regularly provided coach and mail service from the Missouri River area. In 1859, he was elected Territory Representative from the 1st District. He was elected mayor of Denver of Jefferson Territory on December 19, 1859. In January 1860, he began to work with the City Council to establish a municipal government, which was part of the provisional government of Jefferson Territory and subject to laws of Kansas Territory. The three towns of Auraria, Denver, and Highland were consolidated into the city of Denver, which was finalized in March 1860. He founded the Denver Mountaineer, a daily Democratic newspaper which held strong Southern viewpoints. He was a member of the Colorado Pioneers' Society.
When the Civil War began, Moore returned to Missouri and first served with the Missouri State Guards under Sterling Price. He fought in the Battle of Pea Ridge in the battery of soldiers from St. Louis under Captain Emmett MacDonald. During the Battle of Prairie Grove, he was an aide to Colonel Robert G. Shaver. He then became an officer in the Confederate States Army. He was a friend and school mate of General John S. Marmaduke and became his chief of staff and served as his second in Marmaduke's duel with Confederate General Lucius M. Walker. He served with Marmaduke until the Battle of Mine Creek, when the general was captured. He attained the rank of judge adjutant general of Arkansas for six months. Moore received the rank of colonel while serving under General Joseph O. Shelby. He served with marked distinction. After the Civil War ended, and to keep from surrendering their forces, Moore and Shelby served with the French under Maximilian, tried to serve with Shelby, or held back Maximilian's troops in Mexico. He wrote the "Missouri" section of the Confederate Military History.
After the wars
Moore returned to St. Louis and worked for the St. Louis Post-Dispatch and then moved to Kansas City, where he founded the Kansas City Times. He returned to Colorado and lived in Pueblo, where he founded the Pueblo Democrat and the Pueblo Press. He then returned to Kansas City.