The Army Service Uniform (ASU) is a military uniform worn by United States Army personnel in situations where formal dress is called for. It can be worn at most public and official functions, and as an analog for business dress. In combat situations, the Army Combat Uniform is used.
The blue ASU replaces the "Army Green" and "Army White" service uniforms. Originally created in 2008 as a secondary uniform to the former army "class A greens", in the fall of 2010 it started being issued to all soldiers and now is worn army-wide as the official service uniform.
It is based on the current "dress blue" dress uniform. Older antecedents include the uniforms of the Continental Army during the Revolutionary War and the Union Army's during the Civil War. Their influence is apparent in the overall blue theme, the officers' passants (shoulder-straps) and trouser design.
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While Washington was in Philadelphia, one hundred neighbors in Fairfax County (VA), under the tutelage of George Mason, had organized themselves into a voluntary militia—probably the first in the colony—electing Washington their commander. Borrowing the colors of the English Whig party, the Fairfax Independent Company wore blue uniforms with buff facings and white stockings.
Washington used Thomas Webb’s A Military Treatise on the Appointments of the Army as a guide for outfitting this particular unit. Washington would soon accept the additional field command of another four independent companies: in Prince William, Fauquier, Richmond, and Spotsylvania Counties.
In the early days of the U.S. Army, the uniform worn in combat was essentially the same as that worn for everyday duties. This was the common practice with most armies of the time. This changed in modern times, as field uniforms were developed which were more suited for battle.
During the Civil War era, army uniforms were relatively simple. Typically, the same uniform served as a garrison uniform and as a combat uniform. Combat soldiers in the Civil War wore a standard dark blue coat, just like personnel in garrisons or in army offices and headquarters. In the first half of the war, many states supplied their regiments with uniforms, resulting in distinctive jackets and buttons. Rank was indicated by a shoulder strap for officers, and chevrons on the sleeves for non-commissioned officers. Branch or specialty could be indicated by the color of the enlisted badge of rank, or the background color for officers' shoulder straps. Uniform standards were relaxed during the war years, especially on campaign, and men often wore a variety of hats in the field.