“Impracticable, Inhospitable, and Dismal Country” examines the role of the natural environment in the campaign fought along Tygart’s Valley River in West Virginia during the summer and early fall of 1861. In the weeks following the capitulation of Fort Sumter, it became clear that hostilities would break out in present-day West Virginia. Divided political sentiments between secessionists and Unionists, combined with vital transportation avenues including turnpikes, the Ohio River, and the critical Baltimore and Ohio Railroad, forced the region into the crosshairs of regular military operations. As soldiers from both Union and Confederate armies mobilized in West Virginia, they soon began to understand the natural environment would play a critical role in determining the fight there. More than an arena of combat, the natural environment was a third participant in the fight for the Mountain State. This thesis contributes to the subfield of environmental Civil War studies by analyzing the intersection of environment and war in a unique theater of the Civil War. As the role of the natural environment on military operations in West Virginia has not received thorough scholarly attention, this thesis also helps to push forward the historiography of the Civil War in Appalachia. Topography, weather, and disease were all environmental factors that affected command decisions and impacted the common soldier experience. Both sides could alter the landscape into a natural ally, but the Federals were more proficient in adapting to and overcoming the natural environment. Union victories enabled the unimpeded progress of the Reorganized Government of Virginia and the eventual formation of the state of West Virginia.