Andrew; Thank you for the clarification about Michael's letters and affects.
Very sad that Peter burned them. Coincidentally, very like what Robert Todd Lincoln did for much of the correspondence between Mary Todd and Abraham Lincoln and the letters Willie Lincoln wrote to him (Robert) from Springfield and Washington (I just published a book on Willie Lincoln and my great-grandfather, a sgt. in the Pennsylvania Volunteers who was stationed at the White House 1861-62 and was befriended by Willie, who, although younger than Michael when he died, also had great potential).
The book is entitled Mystic Chords of Memory by Donald Motier.
No one has replied to my other query about the origin of Michael's fear of water. Any ideas?
PS: I live in the US and hope to visit Michael's grave someday.
Also, please accept my belated sympathies for the death of your son.