Here's my previously-promised analysis of the starred endnotes!
Predictions for Volume 3 and the future history after it, mostly using the "starred" (alternate-history) endnotes from Volumes 1 and 2. Still to occur from Volume 1 is the death of Robert E. Lee before the war's end, since a Confederate ship was named after him before the war's end. (I love Chapter 8, note 6 from this volume, which included the comment that "Lee never wrote his memoirs". If Tsouras didn't want to completely give it way, he might have said "Lee didn't live to write his memoirs.") Of course Timmy811 may be right, and they may decide to name the ship after a living person…
Concerning Volume 2 endnotes:
Chapter One, Note 19: Woodrow Wilson as the author of a history book is consistent with the Wilson of OTL ("our timeline"), so perhaps he still becomes president.
Chapter One, Note 27: Although Volume 1 commented that the Civil War became a world war in this timeline, the use of the term "World War I" is the first to tell us that there would be multiple world wars. (Also see Chapter Nine, Note 8.) This note also presages Russia's expected entry into the war in Volume 3.
Chapter Two, Note 9: The term "Reconstruction" implies the U.S. occupation of the South after the war, as in OTL. (We already know from Volume 1 notes that the U.S. survives and the Confederacy likely does not.)
Chapter Six, Note 10: The title "Wisconsin in the Civil War and the Great War" ihas multiple interpretation. It could be saying that implies that the Great War (World War I) is considered by history to have started at some point beyond Fort Sumter (either in September 1863 with the British and French entering the conflict, or with the expected future invasion of the Turkish Balkans by Russia). Alternatively, it could mean that WWI will last beyond the defeat of the Confederates (which is the likely endpoint of Volume 3). I am surprised that the term "Great War" was still being used in 1922, since we know that WWII started well before that date (See Chapter Nine, Note 8.)
Chapter Seven, Note 16: We know from endnotes in both volumes that Lincoln lives till at least 1868, since Sharpe's conversations with him last that long. However, I noted in the endnotes for the previous volume that since Lincoln's second term doesn't end until March 4, 1869, there is an implication that Lincoln may die several months before that date. We know from this endnote that John Wilkes Booth is eventually put on trial (presumably for treason); however, he was not arrested after Big Jim Smoke's attempted assassination. So, does this mean he was arrested for being part of that October 1863 plot at some later point, or does Booth himself succeed in 1868? (The book shows a year of “173”, probably a typo for 1873.)
Chapter Eight, Note 6: See my comments in the opening paragraph.
Chapter Eight, Note 17: Unlike Woodrow Wilson, a military history book written by Dwight D. Eisenhower is inconsistent with the type of books Ike wrote in OTL. I would think it likely that Eisenhower never became president in a timeline so distorted politically and militarily by the divergence.
Chapter Nine, Note 8: Here is the motherlode of postwar information. Even though in OTL Zeppelin did observe the use of balloons during Civil War and became a protege of Lowe after the war, the increased use of balloons led to a far greater collaboration here. The use of lighter-than-air aerial bombing in the Battle of Washington leads to "Zeppelins" being used to provide something like the Battle of Britian in 1890. So not only are there at least two world wars, but WWII occurred about 50 years early, with the U.S. apparently on the side of the Germans. (By the way, I’ve noticed many of the alternate-history articles are dated around 1890 – coincidence?)
Chapter Nine, Note 9: An German-language book published in St. Louis in 1889!!! (Hmm...one of those articles dates near WWII...) The translation (something like "The German deed for America: The Wall and the Germans in the Great War") doesn't provide anything we don't already know from the text proper.
Chapter Nine, Note 13: Arthur Freemantle...hmm...so apparently in OTL he was an unofficial British observer who left America for Britain mid-July 1863 (before the divergence point) and eventually wrote a pro-South book on his experiences. I would assume something similar happened here.
Chapter Ten, Note 7: There will be a "Second Battle of New Orleans". In our OTL there was only one Battle of New Orleans, and that was at the end of the War of 1812. Since the October 1863 conflict was in Vermillionville (and the Union evacuated New Orleans after that), I assume that the First Battle of New Orleans is either referring to that battle (which is likely), or two battles in New Orleans are yet to come.
Chapter Eleven, Notes 9 and 21: Okay, Denison publishes an English-language book in Montreal in 1868. At somepoint, however, he "immirgrated to England rather than live in the newly acquired territories of the United States". In Volume 1, there was an endnote from a 1914 paper published about Wolseley’s 1863 lectures published in Toronto by “The Defence Staff” (which today appears to be roughly the Canadian equivalent of the future U.S. Joint Chiefs of Staff), making me erroneously think that Canada stayed out of U.S. hands, but also implying that at some point before 1914 it becomes independent and/or realigned with Britain. As for Quebec, where Montreal is, maybe Quebec declared its independence after the war, with U.S. encouragement?
Chapter Eleven, Note 22: The tense of Seward's title "Lincoln as I Knew Him", published in 1872, implies that Lincoln is dead by this time.
Chapter Twelve, Note 23: Finally, we find out that there will be Battle of Havana in 1864, and that Prince Arthur will once again be captured by Union troops. Could Spain eventually enter the war? I know that in OTL Isabella II was in the early 1860’s still trying to get reparations for the confiscation of the slave ship Amistad and the slaves it was carrying, but Spain had been convinced into neutrality by the Union's arguments that it was politicians from the South who were behind a U.S. movement to annex Cuba. (Alternatively, Timmy811 made a plausible explanation for why there would be a Battle of Havana without Spain entering the war.)