2374 was the year that the Romulans entered the war on the Alliance's side.
Using the handy Excel stardate calculator, I calculate that the exact events (as I recall, the log entry with stardate given by Sisko was two weeks after the fact) occured on approximately stardate 51683.0. The log entry Sisko made was on stardate 51721.3.
[This message has been edited by Caretaker (edited 03-22-2001).]