From the record
“Fort Phantom Hill, also called the Camp on the Clear Fork, is a former United States Army installation located in Jones County, Texas. The fort was established in 1851 as part of a line of forts in Texas to protect migrants passing through the state on their way to California.”
Wikipedia article Fort Phantom Hill, CC BY-SA 4.0.
One of 22 National Register listings published here for Jones County · listed in 1972 · category: Site.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service