Fort Fillmore, located at 32°13′30″N 106°42′52″W,[2][3] was a United States military fortification established by Colonel Edwin Vose Sumner in September 1851 near Mesilla in what is now New Mexico, primarily for the purpose of protecting settlers and traders traveling to California.

Early frontier migrants were under constant threat from attack by local Native Americans, and a network of forts was eventually created by the U.S. government to protect and encourage westward expansion.

In 1855, Union General Ambrose Burnside used the fort as a supply point when he drilled geothermal wells about fifteen miles west of the post.

As they retreated back to Fort Stanton under Major Isaac Lynde, they became desperately thirsty and exhausted.

The remains of the fort were leveled at some later date after a failed attempt by the owner to sell or trade it to the State of New Mexico as a park.