I am on vacation and away from my work station. I will be very much interested in the exact fact line of what this letter says. Burris would have arrived at Fort Delaware on 12 MAR 1865 with the other returning survivors of the Immortal 600. No one got out of Fort Delaware after April 1st, 1865 without taking an Oath of Allegiance. The prisoners would have just barely learned of Lee's surrender by 12 APR 1865. Many prisoners started clamoring to be released since "the war was over" although Lee's surrender was just the beginning of the end which was not complete until 26 MAY 1865 with the surrender of the Trans-Mississippi. The Fort Delaware prison staff immediately went into overdrive to see how many of the prisoners (mainly the officers) they could get to ask to take the oath.
When we get settled in a couple of days, I will be able to access the Society database and see if we show W. R. Burris' record and release date.
Thanks for the heads up!
Hugh