Fort Maginnis was built in 1880 to protect the cattle ranches, the gold mining camps in and around the Judith Mountains and the Carroll Trail.

Stuart was made the general manager of the DHS brand and Stuart located the ranch headquarters on 800 acres (320 ha) on the southern slopes of the Judith Mountains near Flat Willow Creek.

[5][6] The DHS Ranch was one of the largest open range cattle operations in the Central Montana prairie in the 1880s.

[7] The geology of the range includes limestone, sandstone, and siltstone of Cambrian to Cretaceous age which were intruded by alkaline intrusives of monzonite, syenite to tinguaite composition of Cretaceous to Tertiary age.

[8] The mountains were the center of gold and silver mining in the 1800s and current exploration continues.