On the other hand, 1634: The Ram Rebellion by Eric Flint and Virginia DeMarce isn't so much about saving the world (from aliens) as it is about saving a world from the chaos and bloody-minded religious bigotry of the 17th century. This book is, of course, part of the "Ring of Fire" series, in which the small West Virginia town of Grantsville is dumped into Germany in the midst of the Thirty Years War. Adroit diplomacy as well as mechanic arts are required for this little sliver of America to survive, let alone prosper, and as this particular book shows, sometimes stuff just happens. Flint announces his distaste for the Great Man theory of history in the preface, and just as Tolstoy does with War and Peace, Flint uses this novel as an argument against it. Despite this, the book is a fun read while still being an account of an occasionally gory revolution by the peasants, villagers and upper nobility against the predatory barons and Reichsritter who did so much to keep Germany the collection of "pumpernickel principalities" it was, to use Churchill's wonderfully descriptive phrase, until Bismarck came along and pushed the Prussian Hohenzollerns into unifying the place. The "up-time" Americans of Grantsville do have their fingers in the pie, but by and large they're waging memetic warfare against the petty nobles and letting the armed villagers and peasantry deal with the difficult work of toppling the local tyrants while discovering the virtues of religious tolerance and unified, simplified government. Worth reading, but probably difficult going unless you've read 1632 and 1633 first, since the bulk of the book is drawn from legitimized fanfic originally published online in Baen Books' Grantsville Gazette.