Well, technically the Romulan War (and all of Star Trek: Enterprise
) is common to both timelines - things only start changing in 2233 when Nero either does or doesn't appear.
is what the plan for the Romulan War was. A movie starring James T. Kirk's grandfather or great-grandfather, Tiberius Chase. Enterprise NX-01 is at Risa and misses the entire thing
(which lasts a week, ignoring the old Star Trek Chronology
's conjecture that it lasted 4 years). Cameos by Shran and Captain Hernandez. A tiny bit more info is HERE
, detailing Romulan battle tactics.
It's a shame we didn't get to see it, but I think the movies we got instead were far superior.