From the plaque:
To protect the Anza Trail
where it forded the Colorado River, the Spanish founded
a pueblo and mission nearby on January 7, 1781. Threatened
with the loss of their land, the Quechans (Yumas) attacked
this strategic settlement on July 17, 1781. The Quechan
victory closed this crossing and seriously crippled future
communications between upper California and Mexico.
Plaque placed by the State Department of Parks and Recreation in cooperation with E Clampus Vitus, Imperial Valley Pioneers, Phil Porretta & Family, Bureau of Land Management, Yuma County Historical Society and Quechan Tribal Council. May 4, 1980.