John M. Murrin, et al., eds., Liberty Equality Power: A History of the American People, 2nd ed. vol. 1 (Fort Worth: Harcourt Brace, 1999), 457.
Unable to protect their freedom through legal means, many blacks, with the support of white allies, resorted to flight and resistance. Thousands of northern blacks fled to Canada - 3,000 in the last three months of 1850s alone - sometimes under the very nose of slave-catchers. In 1852 slave-catchers arrested a fugitive who had taken the name Shadrach when he escaped from Virginia a year earlier. They rushed him to the federal courthouse, where a few deputy marshals held him, pending a hearing. But group of black men broke into the courtroom, overpowered the deputies, and spirited Shadrach out of the country to Canada. This was too much for the Fillmore administration. In April 1851 another fugitive, Thomas Sims, was arrested in Boston, and the president sent 250 soldiers to help 300 armed deputies enforce the law and return Sims to slavery.