Depredations of this sort caused alarm among slaveholders. They sought to deter their chattels from flight by talking freely before them about the rigors of the climate and the poverty of the soil of Canada. Such talk was wasted on the slaves, who were shrewd enough to discern the real meaning of their masters. They were alert to gather all that was said, and interpret it in the light of rumors from other sources. Thus, masters themselves became disseminators of information they meant to withhold. In this and other ways the slaves of the border states heard of Canada. The sale of some of these slaves to the South helps to explain the knowledge of Canada possessed by many blacks in those distant parts. When Mr. Ross visited Vicksburg, Mississippi, he found that "many of these negroes had heard of Canada from the negroes brought from Virginia and the border slave states; but the impression they had was that, Canada being so far away, it would be useless to try to reach it."[63] Notwithstanding the distance, the number of successful escapes from the interior as well as from the border slave states seems to have been sufficient to arouse the suspicion in the minds of Southerners that a secret organization of abolitionists had agents at work in the South running off slaves. This suspicion was brought to light during the trial of Richard Dillingham in Tennessee in 1849.[64] The labors of Mr. Ross several years later gave color to the same notion. These facts help to explain the insistence of the lower Southern states on the passage and strict enforcement of the Fugitive Slave Law in 1850. [63] Dr. A. M. Ross, _The Recollections and Experiences of an Abolitionist_, p. 38. [64] A. L. Benedict, _Memoir of Richard Dillingham_, p. 17.