With the outbreak of the Civil War, he enlisted in the Union Army on August 16, 1861, serving as lieutenant colonel of the Eighteenth Regiment, Indiana Volunteer Infantry.

He distinguished himself at the Battle of Pea Ridge by leading the 18th Indiana in a counterattack to recapture two guns lost from the Peoria battery.

[1] After garrisoning Missouri for the fall and winter, the 18th Indiana was attached to Grant’s army endeavoring to cross the Mississippi and seize Vicksburg.

The 18th Indiana fought at Port Gibson and Champion Hill and took part in the siege operations around Vicksburg, where he commanded a brigade commended for valorous actions during the initial assault upon the enemy fortress in May 1863.

[2] During Sheridan’s campaign to clear the Shenandoah Valley, Washburn commanded the 4th Brigade during heavy fighting at the battles of Opequon, Fisher’s Hill and Cedar Creek.

List of American Civil War brevet generals (Union) This article incorporates public domain material from the Biographical Directory of the United States Congress