William Horace Warner (8 May 1812 – 26 September 1849) was an officer in the United States Army's Corps of Topographical Engineers.

In 1849, he led an Army survey party north from Sacramento through the uncharted country of northeastern California into south central Oregon.

As a topographic engineer officer, Warner was placed in charge of a project to improve the harbor at New Bedford, Massachusetts.

Later that year, Warner was sent back to Florida to support action in the ongoing war with the Seminole people.

After finishing that project in 1845, Warner was sent to survey the boundary between the United States and the British provinces of Canada.

[6][7] In October 1848, Warner joined Lieutenant Sherman, Colonel Richard B. Mason (the military governor of California), and a civilian named Norman S. Bestor to form a mercantile company.

After the company was formed, the business was turned over to Bester to run with the help of a clerk who had previously worked for Warner.

[8] In January 1849, Warner participated in the first criminal trial held in Sacramento County, California under United States law.

The trial prosecuted a store keeper named Charles F. Pickett for the murder of a rival merchant.

[1][10][11] Warner's second-in-command for the expedition was Second Lieutenant Robert S. Williamson, who was also a West Point trained topographic engineer.

When the expedition reached the Goose Lake Valley, Warner decided to separate the party into two teams in order to cover more ground.

Warner and his men left the valley at its southern end, heading toward the Oregon–California border, which was only a short distance away.

In 1850, an army expedition under the command of Captain Nathaniel Lyon was sent out to recover Warner's body, but it was not found.

[12][13][16] In the summer of 1864, lieutenant colonel Charles S. Drew was ordered to lead a large reconnaissance patrol east from Fort Klamath to explore southeastern Oregon.

After a difficult winter, the army moved the post to a new location near Honey Creek, on the west side of the Warner Valley.