Fourth, in late March and early April 1865 the Confederate secret services, having abandoned abduction plans, plotted to kill Lincoln (and hopefully his entire Cabinet) by exploding a mine near the White House. This plot to assassinate Lincoln had been personally approved by Jefferson Davis and other top Confederate leaders. The plan failed because the explosives expert from a secret service, the Confederate War Department’s Torpedo Bureau (at that time mines were called torpedoes), who had been detailed to detonate the mine, was, while being escorted to Washington, D.C. by Confederate cavalry, unexpectedly captured by Union cavalry on April 10 a mere 15 miles from the District.
Wilkes, Donald E. Jr., "Lincoln Assassinated!, Part 2" (2005). Popular Media. Paper 122.