"...during the Civil War he [Dr. Alexander M. Ross, a Canadian] rendered most valuable services to the Federal Government as a secret agent in Canada watching the operation of Confederate agents there." [Source]
Dr. Ross's recollections included this directive from President Abraham Lincoln:
"In the meantime, help us to circumvent the machinations of the rebel agents in Canada. There is no doubt they will use your country as a communicating link with Europe, and also with their friends in New York. It is quite possible also that they may make Canada a base, to annoy our people along the frontier. Keep us well posted of what they say and do."
"Immediately upon my arrival in Montreal, I sought opportunities to familiarize myself with the names, habits, and occupations of the various Confederates in Canada. I had but little difficulty in accomplishing this purpose, as the Confederates looked upon all Canadians as their friends."
The principal Confederate agent in Canada at that time was an ex-Member of Buchanan's administration.
Did Dr. Ross encounter one of my relatives? Robert Maxwell Martin, a Confederate agent in Canada, and I are both descendants of William Roark.
The CIA weighs in on the spies.
Dr. Alexander M. Ross was also affiliated with the abolitionist John Brown.