For more than half a century before the building of the great Pacific
railways, engineer officers were engaged in making surveys and
explorations in the great unknown country west of the Mississippi
River, and the final map of that country was literally covered with a
network of trails made by them. Several of these officers lost their
lives in such expeditions, while others lived to become more famous as
commanders during the great rebellion. Generals Kearney, J.E.
Johnston, Pope, Warren, Fremont and Parke, and Colonels Long, Bache,
Emory, Whipple, Woodruff and Simpson, Captains Warner, Stansbury,
Gunnison and many other officers, generally in their younger days,
contributed their quota to the geographical knowledge of the country,
and made possible the wonderful network of railways guarded by
military posts that has followed their footsteps. Their reports fill
twelve large quarto volumes.