In 1856 United states sent a commission of 3 officers to study the war. They managed to obtain letters of introduction from British but not from French. After a long detour in Russia(to inspect Krondstadt defences and get permission to enter Russian camp in Crimea) they finally managed to reach Sebastopol. However by that time city has fallen and they could only inspect fortifications, positions and such. They did not get chance to see any of the fighting in the actual war.
In general I found information about this to be hard to come by. There is and old thesis that has a summary of what happened
http://www.dtic.mil/dtic/tr/fulltext/u2/a133315.pdf . The three men were quite interesting. Mordecai retired to avoid serving on either side of the war, Delafiel published a book on European Art of war in 1854, 55, 56
http://www.dtic.mil/dtic/tr/fulltext/u2/a133315.pdf (I am planning to read it), third was General McClellan(captain at the time), the one and only.
Often people call ACW as the first "modern" war and yet in Crimea almost everything that we see in ACW happened already, at least on tactical level. In the period in between seems like a lot of could be done to reform training and organization of the army. What we see even at Gettysburg seems like it was already obsolete in Crimea, range at which rifle fire is effective. Advancing in closed order, field fortifications etc
I am curious if anyone written or explored a TL where commission is sent earlier. Perfect time would be 1854 to be with the Allied landing in Crimea and see full extent of war and siege of Sebastopol. Be present at Alma and after? Seem like it could have massive impact on US and beginning stages of ACW.
Other possibility is one of the generals who joined the Confederates being present on the commission. Delafiel book was apparently suppressed because it was feared that it would be used by Confederates. What if someone who later joined Confederacy was sent in his place?
If someone knows about good things to read not the topic please feel free to share as well.