Down the long line, the smoke of muskets and artillery boiled from the landscape, marking the collision point of Union and Confederate forces at the Battle of Gettysburg.

That moment was captured in an 1887 chromolithograph by Thure de Thulstrup (1848-1930), a Swedish-born artist who became an illustrator for Harper's Weekly after the Civil War.

And on Thursday, a reproduction of it appeared on a newly issued stamp from the U.S. Postal Service, commemorating the 150th anniversary of the epic clash.

A second newly issued stamp, marking the 150th anniversary of the Battle of Vicksburg, is a reproduction of an 1863 lithograph by Currier & Ives titled Admiral Porter's Fleet Running the Rebel Blockade of the Mississippi at Vicksburg, April 16th, 1863.

The Gettysburg and Vicksburg stamps have been issued as Forever stamps, which are always equal in value to the current first-class mail 1-ounce price, postal officials said.

". . . We are humbled by the opportunity to dedicate this new stamp honoring those who made the ultimate sacrifice so our country could be whole and we could all prosper," Jeff Williamson, the Postal Service's chief human-resources officer and executive vice president, said of the Gettysburg stamp.

Thulstrup's work was one of a series of popular prints commissioned in the 1880s by Boston publisher Louis Prang & Co. to commemorate the war.

Customers may purchase the Civil War Sesquicentennial 1863 collectible Forever Souvenir Stamp sheet at usps.com/stamps, at 800-STAMP-24 (800-782-6724) and at post offices nationwide.

This issuance is the third of a five-year series commemorating the 150th anniversary of the Civil War. The sheet of 12 stamps includes the two stamp designs, depicting Gettysburg, the largest battle of the war, and Vicksburg, a complex Union campaign to gain control of the Mississippi River.

The Postal Service began the Civil War Sesquicentennial Forever Stamp series in 2011 with the issuance of the Fort Sumter and Battle of Bull Run stamps. Last year, stamps memorializing the Battles of Antietam and New Orleans were issued.

A souvenir sheet of two stamp designs will be issued for each year of the war through 2015.

The background image on the 1863 souvenir sheet is a photograph taken by Mathew Brady on July 3, 1863, shortly after the Battle of Gettysburg, of three captured Confederate soldiers.

The souvenir sheet includes comments on the war by Abraham Lincoln, nurse Clara Barton, Union soldier Rufus R. Dawes, and Confederate soldier William Tunnard.

Contact Edward Colimore

at 856-779-3833 or ecolimore@phillynews.com.