The use of wool in the uniform meant that the uniforms were not suited to the warm climates that were common in the South. This contributed to many Confederate soldiers suffering from heatstroke on long marches. However, one understanding of the heavy woolen garments is that after the marching during the day time, when the soldiers would rest at night and cool themselves down, the thermal-shock could render some men unable to function the next day. As such, the woolen garments would protect the soldiers from this, and keep them able to keep marching the next day to fulfill their duties. This was also the case with the better equipped U.S. Army. Many Confederate soldiers started the war with frock coats. However, cloth shortages and wartime wear insured that, by 1863, waist-length cadet gray or butternut shell jackets were generally worn by Confederates in the Eastern and Western Theater. Examples of frock coats being worn by enlisted men can be seen in photographs taken after the battles of Gettysburg, (1863), and Spotsylvania, (1864).