Time for Patriots offers a combination of both traditional AH and introduces an alternative life for Mozart (with hints of similar effects on Hayden and Beethoven). A physics experiment gone awry sends North Shore Military Academy back from the 21st Century to 1770. Their modern copier allows convincing counterfeiting, and neighbors carried back with them aid plans to interfere in the Revolution. None of this is tremendously different than one might expect, although black students have to pretend to be the slaves of those they command as the group infiltrates.
In our history Mozart had a very poor medical history, and died shortly before his 37th birthday of a disease that may have been anything from scarlet fever to pneumonia. (The idea he was poisoned is a 20th Century fiction with no evidence--in fact, Salieri was later the music teacher of Mozart's younger son.) History indicates he started looking ill in late September, and died in early December of 1791.
In Time for Patriots a group from the military academy decide, in violation of the academy's rules, to prolong Mozart's life. They join a flotilla sent by Washington to discourage Barbary pirates, do a convincing job on the Bey of Algiers, and on a "show the flag" visit to Naples, slip away and head for Vienna.
In Innsbruck an Austrian national hero, Andreas Hofer, is warned against his ultimate betrayer. This introduces an unintended butterfly effect that has major consequences later.
The three Americans meet Mozart's wife, Constanza, and treat the abscess on her ankle successfully. Mozart is hired to write a march for the military academy while preserving their anonymity. Mozart invites them to join him and his theatrical producer, Schickaneder, at a rehearsal followed by indulging at a bierundweinstube. The conversation makes Mozart curious about their backgrounds and motives. As he falls ill they treat him with modern medicine (he is a really big pain in the rump as a patient).
Mozart survives, and completes not only the march they asked for, but also an opera about Benjamin Franklin, and many other works before his death during "Napoleon's second siege of Vienna", in 1805. His sometimes librettist, Da Ponte, however, repeats his experiences in OTL with no noticeable changes (defrocked for fooling around with women, marrying an English woman, and more) other than doing the Franklin libretto. Thus he flees Europe and settles in New York, where he winds up teaching at Columbia, just as in OTL. He eventually runs into one of the three who had visited Vienna in 1791, and learns the true story. The written records of this turn up in 1926, a month after the first lunar landing.
In 1811 the time travelers send an agent to New Orleans at the behest of President Madison, to investigate rumors of spies and agents from many nations active there. The agent watches the Great Comet of 1811, amused by the downtimers' opinions of it, but maintains his silence. He stays at the House of the Rising Sun, quite innocent of knowledge of its history. He learns, while checking out the spies, one of whom tries to kill him.
While the core group of time travelers try to prevent wars, the butterfly consequences of the warning given in Innsbruck result in the creation of the Tyrolean Republic, which allies with Bavaria and France. World War I never happens. Back in the USA the grandson of one of the time travelers is elected President in 1848, and uses tax money to purchase slaves in the four states still having slavery, averting the Civil War.
Mozart had sent copies of all his new works to the military academy's Music Director, not just the special march he wrote for the school. A century later a music professor from Columbia and his history professor wife visit the academy to study Mozart's works, and find evidence of time travelers' interventions. Will this be revealed to create chaos?
* * *
Thomas Wm. Hamilton a retired professor of astronomy, a planetarium director and author of Time for Patriots (Strategic Books, 2011). His anthology of 28 stories of science fiction, fantasy, and satire, The Mountain of Long Eyes, 2012, has three short sequels to the above novel. He has an asteroid; Asteroid 4897 named after him called TomHamilton.