It's called the American Civil War, but as it turns out, some Canadians had a pretty significant part in it, too.

The conflict, which lasted from 1861 to 1865, was an existential battle to determine whether the United States of America would survive or splinter into a number of independent confederate states.

The war pitted the Unionist north against southern Confederates and killed an estimated 620,000 people, according to the Civil War Trust.

John Boyko, author of Blood and Daring: How Canada fought the American Civil War and Forged a Nation, writes that roughly 40,000 Canadians participated in the conflict.

To mark the 150th anniversary of the Union army's victory, as well as the assassination of U.S. President Abraham Lincoln on April 14, 1865, here's a look at some of the Canadians who had a hand in the war.

Edward P. Doherty, captured John Wilkes Booth


Edward Doherty may have been the highest-profile Canadian during the conflict. Little is known about his origins, but according to the Civil War Interactive web site, Doherty was born in Canadian territory in 1840 and was in New York when the war began.

Doherty served as a private in Company A of the 71st New York Regiment, which saw action in the first Battle of Bull Run near Manassas, Va.

He later became a first lieutenant with the 16th New York Cavalry, which was assigned to defend Washington, D.C. But his most illustrious posting was still to come.

On April 24, 1865, 10 days after Lincoln's assassination by John Wilkes Booth, Doherty was ordered to form a detachment to capture Booth and any collaborators.

Doherty and two dozen other members of the 16th N.Y. caught up with Booth and David E. Herold two days later in a Virginia tobacco barn, where Herold surrendered and Booth was killed, according to Doherty's report.

Doherty, who received a $5,250 reward for finding Booth, remained in the military until 1870. He died in 1897 and is buried in Arlington National Cemetery in Virginia.

Anderson Ruffin Abbott, Canada's first black surgeon


Anderson Ruffin Abbott

Anderson Ruffin Abbott was Canada's first black physician and eventually made the acquaintance of U.S. President Abraham Lincoln.

Anderson Ruffin Abbott was Canada's first black physician and became one of only 13 black surgeons to serve in the Civil War.

According to the Dictionary of Canadian Biography, Abbott was born in Toronto in 1837 to free people of colour who had escaped racism in Alabama.

He applied to be an assistant surgeon in the Union Army in February 1863, and was accepted two months later as a civilian surgeon with the United States Colored Troops.

Between June 1863 and August 1865, Abbott served in Washington, D.C., and eventually worked in a hospital in Arlington, Va.

Abbott earned a solid reputation and gained prominence in Washington social circles, even making the acquaintance of President Lincoln.

After Lincoln's assassination, the president's widow, Mary Todd Lincoln, presented Abbott with the shawl that Lincoln wore to his 1861 inauguration.

Sarah Emma Edmonds, fought as a man


Sarah Emma Edmonds

Born in New Brunswick, Sarah Emma Edmonds spent the American Civil War disguised as a soldier named Franklin Thompson. (Library and Archives Canada)

Sarah Emma Edmonds (née Edmonson) spent much of her life masking her true identity. Born in New Brunswick in 1841, Edmonds left home in 1857, apparently escaping an abusive father and the threat of an arranged marriage.

She emigrated to the U.S., but fearful of being found out she disguised herself as a man named Franklin Thompson.

When the Civil War broke out in 1861, Edmonds-as-Thompson joined the 2nd Michigan Infantry.

During the war, she nursed wounded soldiers, worked as a courier and even fired a gun on a number of occasions.

In 1863, Edmonds and the 2nd Michigan were sent to fight in Kentucky, where Edmonds contracted malaria. Worried about being discovered, she abandoned her comrades and, as "Franklin Thompson," was charged with desertion.

In 1864, she published her memoirs, which, according to the Civil War Trust, "detail several of her exploits behind enemy lines throughout the war, disguised variously as a male 'contraband' and an Irish peddler."

Years later, an Act of Congress cleared "Franklin Thompson" of desertion charges and Edmonds was awarded a pension in 1884.

Calixa Lavallée, O Canada composer fought on the Union side


Calixa Lavallee

Although best known as the composer of O Canada, Calixa Lavallee also fought in the famously bloody civil war battle at Antietam, Md. in 1862. (Courtesy of Bibliothèque et Archives Nationales du Québec)

Born in Verchères, Lower Canada, in 1842, Calixa Lavallée was a celebrated musician who is best known as the composer of O Canada, our national anthem.

According to the Dictionary of Canadian Biography, Lavallée travelled to the U.S. in 1857 and won a music competition in New Orleans, which led to a musical tour of the Americas and the West Indies.

In 1861, he enlisted in the 4th Rhode Island Volunteers of the Union Army, eventually becoming a lieutenant.

In 1862, he fought in the famously bloody battle at Antietam, Md., where he is thought to have sustained a leg wound. Lavallée was honourably discharged in October 1862.

Lavallée came back to Lower Canada, but he eventually returned to the U.S., where he married an American woman and worked as a music teacher and performer in Boston, where he died in 1891.

Benjamin Wier, Confederate trader, blockade runner


Benjamin Wier

During the American Civil War, Halifax businessman Benjamin Wier gave Confederates access to ship repair facilities in return for cotton supplies that he could export to Britain. (McCord Museum)

Born in 1805, Benjamin Wier was a prominent and controversial Halifax entrepreneur and politician who collaborated with Confederate blockade runners during the Civil War.

According to the Dictionary of Canadian Biography, "Profit rather than patriotism probably motivated this activity."

Wier gave Confederates access to ship repair facilities in Halifax; in return, Confederates provided him with cotton supplies, which he could sell to Britain. It was a lucrative arrangement for Wier, but it required that he cut business ties with New England.

After the South lost the war, Wier managed to re-establish trade with northern businesses — but he couldn't appease the U.S. government, which refused to grant him a visa to step on American soil.