Yesterday, a Canadian soldier fell in the service of his country. He didn’t die on some far-off battlefield. A cowardly murderer shot him down as he stood guard honoring his nation’s war memorial.

Americans should mourn this loss as well. We face a common threat. But, more importantly we lost a brother-in-arms. No nation has stood by America more than Canada. Few countries have fought shoulder-to-shoulder with us more often.

>>> See Canada’s Emotional Welcome for Hero Who Killed Terrorist

In World War I, American Doughboys fought a trench away from their Canadian comrades. During World War II, from the beaches of Normandy to the Rhine River, GIs and Canadian troops fought side-by-side to liberate Europe.

Many Canadians, in fact, crossed the border to join the American ranks—because the Yanks had better “kit.” One extraordinary young man was Lawrence Samuel Gordon from Eastend, Saskatchewan, Canada.

In 1942, when his brother joined the Canadian Army, Sam Gordon became Private Gordon in the U.S. Army. Assigned to Reconnaissance Company, 32nd Armored Regiment of the 3rd Armored Division, he landed on Omaha Beach on June 23, 1944, fought his way through Normandy and was missing-in-action during the battle of the Falaise Gap.

Gordon’s name remained on the Wall of Missing for almost 70 years until this past June, when his remains were discovered in a German war cemetery and this Canadian-American hero came home.

Better known was the elite 1st Special Service Force, a composite unit of Canadian-American commandos popularly known as the Devil’s Brigade.

Our partnership didn’t end with World War II.

Canadians also participated in the Korean War. In 1991, Canada sent 4,500 troops to assist us in what we called Operation Desert Storm and Ottawa called Operation Friction.

Canadian special forces were some of the first on the ground in Afghanistan after 9/11. Canadians served side-by-side with Americans for 12 years in that theater.

On the homefront, the partnership between the U.S. and Canada could not be more important. The U.S. and Canada share a joint military command, NORAD, which keeps watch on the air and sea approaches to North America.

As part of the “Five Eyes” intelligence cooperative that also includes Australia, New Zealand and the United Kingdom, our countries participate in the most effective partnership in the free world. Cooperation on law enforcement, border security and disaster response is just as robust.

Today, it would be fitting stand up, turn north and say, “We are all Canadians.” Americans are blessed to share a continent with such a brave and honorable people.