Uniform of the Union Army

The Uniform of the Union Army was widely varied and, due to limitations on supply of wool and other materials, based on availability and cost of materials during the United States Civil War.
Generalization.
The standard U.S. Army uniform at the outbreak of the war had acquired its definitive form in the 1858 regulations. It consisted of a Campaign Uniform, a Parade (Dress) Uniform, and a Fatigue Uniform.
During the war, enforcement of uniform regulations was imperfect. Uniforms were adapted to local conditions, the commander's preference, and what was available. For example, shoulder straps began replacing epaulets in dress occasions. As a result, almost any variation of the official uniform could be found as officers and men abandoned some items, adopted others and modified still others.
Described in general terms this uniform consisted of:
Service and campaign.
The service and campaign uniform consisted of the following:
Parade order.
The parade uniform consisted of the following:
Fatigue.
The fatigue uniform consisted of the following:
In general terms, as the war went on, the service uniform tended to be replaced by the cheaper and more practical fatigue uniform.
Description.
Footwear.
The enlisted infantry uniform was completed with a black leather belt and oval buckle with the letters US. Officers, NCOs and cavalry troopers were equipped with a sword belt with a rectangular buckle with eagle motif.
Ranks and insignia.
Officers.
Rank was displayed on epaulettes (dress occasions) or shoulder straps(field duties): no insignia for a second lieutenant, one gold bar for a first lieutenant, two gold bars for a captain, a gold oak leaf for a major, a silver oak leaf for a lieutenant colonel, a silver eagle for a colonel and one, two or three silver stars for a general, depending on his seniority.
The color of the shoulder strap fields – with trims in gold braid – were as follows:
Contemporary photographs and a Winslow Homer painting, "Playing Old Soldier", show staff officers occasionally added their departmental initials within the shoulder straps between the rank insignia. "M.S." for "Medical Staff" appears to have been the most common.
With the exception of slight changes to the representing insignia for the more junior commissioned grades as well as additional color combinations for new career fields, the shoulder strap insignia and color scheme survives largely unchanged in the modern era on the Army Service Uniform.
Individual officers would sometimes add gold braid Austrian knots on their sleeves but this practice was uncommon as it made them easy targets and risked friendly fire as this was the standard insignia for Confederate officers.
Nevertheless, many officers personalised their uniforms. For instance, the "Jeff Davis" hat would be pinned back with eagle badges. Many cavalry officers were adorned with eagles and belts with eagle motifs. The designs were based on the Great Seal of the United States.
Non-commissioned officers.
Ranks were worn as chevrons on the right and left sleeves above the elbow. They were colored according to service branch:
Brass shoulder scales were worn on dress uniforms, with different features to signify enlisted ranks. Shoulder scales were not normally worn on service or fatigue uniforms. When in full dress and sometimes also in battle, Sergeants in non-mounted service branches carried the M1840 NCO Sword suspending on a leather belt (except for Hospital Stewards who carried a special sword model). Additionally all ranks above Sergeant (i.e. First Sergeant, Ordnance Sergeant, Hospital Steward, Sergeant Major etc.) wore crimson worsted waist sashes (In the Confederate States Army, all Sergeant ranks wore swords AND worsted waist sashes: red for Artillery and Infantry, yellow for Cavalry).
Corps.
Corps badges were originally worn by Union soldiers on the top of their army forage cap (kepi), left side of the hat, or over their left breast. The idea is attributed to Gen. Philip Kearny who ordered the men in his sew a two-inch square of red cloth on their hats to avoid confusion on the battlefield. This idea was adopted by Gen. Joseph Hooker after he assumed command of the Army of the Potomac, so any soldier could be identified at a distance, and to increase troop morale and unit pride – the badges became immensely popular with the troops, who put them anywhere they could, and the badges accomplished the objectives they had been created for, and the idea soon spread to other corps and departments.
Gen. Daniel Butterfield the task of designing a distinctive shape of badge for each corps. Butterfield also designed a badge of each division in the corps a different color.
The badges for enlisted men were cut from colored material, while officer's badges were privately made and of a higher quality. Metallic badges were often made by jewelers and were personalized for the user. The badges eventually became part of the army regulations.
Division badges were colored as follows:
European and civilian influence.
The uniform itself was influenced by many things, both officers' and soldiers' coats being originally civilian designs.
Leather neck stocks based on the type issued to the Napoleonic-era British Army were issued to the regular army before the war. These were uncomfortable, especially in hot weather, and were thrown away by the men at the first opportunity to be replaced with cotton neckerchiefs, bandanas or (in the case of officers) neckties or cravats.
The basic cut of the uniform adopted in 1851 was French, as was the forage cap worn by some men, and the frock coat was a French invention. However, some parts of the French uniform were ignored, such as enlisted men wearing epaulettes and collar ornaments.
The army went even further than simply having a French-influenced uniform, with some regiments wearing French Imperial Guard voltigeur uniforms, or many even wearing zouave uniforms, such as the 62nd Pennsylvania Infantry, 63rd Pennsylvania Infantry, New York Fire Zouaves as well as the 18th Massachusetts. These consisted of a short blue jacket with red facings, fez, red or blue pants, a red sash and a blue waistcoat with brass buttons or alternatively a red overshirt.
The late-war sack coat was copied from the fatigue jacket worn by the 19th century Prussian Army.
The Hardee hat was inspired by the headgear of the Danish Army but was later abandoned.