Breckenridge being charged with Treason was his impetus for fleeing to Cuba at the end of the war.
Burke Davis wrote a great book called The Long Surrender which gives a good account of the flight south with many anecdotes of Breckenridge and Judah Benjamin travelling down into the Keys.
Meck library has it, but only as an e-book. I don’t want an e-book!
I have that book.