In the early-morning hours of Feb. 2, 1915, German agent Werner Horn and his Irish accomplice planted a large satchel of explosives on the CPR train bridge between Vanceboro, Maine, and St. Croix, N.B., says Brent Wilson, director of the New Brunswick Military Heritage project at the University of New Brunswick's Gregg Centre for the Study of War and Society.
They thought they could take out a strategic supply line to the Canadian war effort, says Wilson.
Japan had recently entered the war and the conspirators misguidedly thought a Japanese army might soon be using the rail line to get to the Western Front.
The group actually planned to destroy several bridges along the New Brunswick-Maine border, including those in St. Stephen, Debec and Perth Andover.
The conspirators gathered beforehand in Portland, Me., where the plan was actually given up, partly due to the cold, windy weather, says Wilson.
Horn, however, missed that meeting, says Wilson, and didn't realize the operation had been cancelled.
The bomb went off, damaging, but not destroying the bridge. It was closed for a few days for repairs. It also shattered shop windows in Vanceboro and St. Croix.
It didn't take long for the authorities to figure out who was behind the incident.
They had seen Horn arrive in the community a few days earlier and were suspicious of him already. He was quickly arrested by Maine police before he had a chance to move on to St. Stephen-Calais.
Put on trial in Fredericton
Horn was put on trial in the U.S. for the property damage caused in Vanceboro, and held for a few years, during which time the Canadian and British governments presented the Americans with arguments he was part of a major German government conspiracy, using the U.S. as a springboard for espionage against Canada.
Three or four years later, Horn was extradited to New Brunswick. He was put on trial in Fredericton, convicted and sentenced to 10 years in the Dorchester Penitentiary.
The German government interceded on his behalf, and by 1921, Horn was deported to Germany, a very sick man. He had been officially classified as insane, but was later discovered to be in the advanced stages of syphilis, says Wilson.
Horn faded into history, says Wilson, but the effect of his attack was to help awaken American officials to the fact that Germans were using agents, including the military attaché in Washington, Franz von Papen, to organize activities aimed at conducting attacks on Canada.
Von Papen was said to be the mastermind of the bombing.
The incident was a clear violation of American neutrality, says Wilson, and served to worsen relations between Germany and the United States and push the Americans slowly towards supporting the Allied cause.
The U.S. eventually entered the war in 1917.