An outstanding original Civil War forage cap in fine, untouched condition, retaining its original leather sweatband and linen liner. The crown is marked with the period-applied designation "B 10th," identifying the company and regiment. Although the previous owner stated the cap was discovered in Ohio, this provenance cannot be documented and should be regarded as anecdotal.The leather sweatband remains present but has become loose in several areas and would benefit from professional stabilization. Paper clips have been temporarily used to prevent additional separation without causing further damage. The most remarkable feature of this cap is its rare field-installed patented metal ventilator, a private-purchase device marketed to soldiers seeking relief from the heat during long summer marches. Original Civil War forage caps retaining these ventilators are exceptionally scarce, as few survive today with the device still intact. Their rarity and distinctive appearance make them highly desirable among advanced Civil War headgear collectors. Overall, this is an attractive and seldom-encountered example of a soldier's personalized wartime equipment.