If the US Postal Service stays in business long enough, it will issue a pair of Civil War commemorative stamps for each year of the sesquicentennial. The two 2011 stamps (the firing on Fort Sumter, and First Bull Run) commemorating 1861 were gorgeous, and the USPS has just announced the 2012 stamps commemorating 1862, which become available in April (after the first class letter rate goes up a penny).
As you can see above, they commemorate the capture of New Orleans and the battle of Antietam. The New Orleans stamp uses as its illustration a detail from this Currier and Ives lithograph alternately titled "The Splendid Naval Triumph on the Mississippi, April 24th, 1862" and "Farragut's Naval Triumph on the Mississippi, 24th April, 1862," published shortly after the event. Farragut's splendid triumph on this day was that he made it past Fort Jackson and Fort St. Philip, both of which guarded New Orleans, thus making its surrender to Union forces inevitable.
Sheridan's Ride." It shows the charge of the Iron Brigade of the West early in the morning on the day of the twelve-hour battle, the bloodiest day in the history of American combat and without a doubt the most important military event of 1862. According to the authoritative Fox's Regimental Losses, the Iron Brigade of the West, composed of five regiments from Wisconsin, Indiana and Michigan, suffered in proportion to its numbers the heaviest losses of any Union brigade in the war.
Dunker Church, house of worship for a pacifist anti-slavery sect of full-immersion Baptists (hence "dunkers") that lay in the midst of the battlefield. Over 12,000 men would die that morning in the immediate vicinity of this building. Here it is in an Alexander Gardner photograph taken two days after the battle, a photograph that Thulstrup may well have studied when making his painting 25 years later.
The Dunker Church that is today part of Antietam National Park is a reproduction; the original was destroyed by a storm in 1921.