WASHINGTON — Months after the Emancipation Proclamation was signed 150 years ago, the first unit of black Northern soldiers was organized as the 54th Massachusetts Regiment and went on to fight at Fort Wagner in South Carolina during the Civil War.

The group’s memory is enshrined in the 116-year-old bronze Shaw Memorial by Augustus Saint-Gaudens on the Boston Common. It was built to honor Col. Robert Gould Shaw, who led the regiment and died in battle.

Now, the National Gallery of Art in Washington has organized the exhibition “Tell it With Pride,” which will be on display until Jan. 20, to explore the black soldiers honored in the memorial.

The gallery holds and exhibits Saint-Gaudens’ original painted plaster sculpture of the Shaw Memorial, which won a grand prize for sculpture at the 1900 Universal Exposition in Paris. It is considered among the finest examples of 19th century American sculpture.

The museum has amassed photographic portraits and writings from across the country of many of the soldiers and their Civil War-era recruiters and teachers, who included Frederick Douglass, Sojourner Truth and Harriet Tubman. An original copy of the Emancipation Proclamation that was among those sold to raise funds for Union troops also is displayed, as well as the first Congressional Medal of Honor awarded to a black soldier after the battle at Fort Wagner.

“Until President Abraham Lincoln signed the Emancipation Proclamation on Jan. 1, 1863, none of these African-American men had been allowed to wear the Union blue; none had been allowed to carry a gun to defend their country; and even their very bravery and their dedication to their country had been questioned,” curator Sarah Greenough said at an exhibition preview. “Yet their heroic stance at Fort Wagner began to silence such questions.”

The battle’s results were devastating, though. About a third of the regiment’s soldiers sent into battle were killed, wounded or missing by the end as the Union forces were defeated.