The Hardee hat, also known as the Model 1858 Dress Hat and sometimes nicknamed the "Jeff Davis", was the regulation dress hat for enlisted men in the Union Army during the American Civil War. The Hardee hat was also worn by Confederate soldiers. However, most soldiers found the black felt hat to be too hot and heavy and shunned its use, preferring a kepi or slouch hat. In the Union Army, the most prominent wearers of the Hardee hat during the war were the soldiers of the "Iron Brigade", also known as the Black-Hats. However, the unadorned, plain and often field-modified Hardee hat was worn by Union troops especially in the Western theater.