One way in which circumstances were different from when Lincoln gave the first address was that "<span>C. For the first address, war was not imminent," since many still maintained hope that the Union would be preserved. </span>
One significant advantage that Frederick Douglass had over many other slaves was "literacy," since his ability to read and write eloquently allowed him to make forceful and compelling arguments against slavery.
So they couldn't be captured and interrogated, and the enemy could then learn the language they spoke over and know the orders given to US troops.
