From the record
“Camp Nichols, also known as Fort Nichols or Camp Nichols Ranch, was a short-lived historic fortification located in present-day Cimarron County, Oklahoma, about 3 miles (4.8 km) northwest of the community of Wheeless, Oklahoma. It was built by New Mexico and California volunteers under the command of Col.”
Wikipedia article Camp Nichols, CC BY-SA 4.0.
One of 2 National Register listings published here for Cimarron County · listed in 1966 · category: Site · a National Historic Landmark.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service