Start in 2152, not with the T’sannu. Describe the Romulan colonization and expansion program, and the UE advancement.
Somewhere Out There
Romulans start moving towards Vulcan. The reunification movement. Imperializing the colonies on Sotarek and Chaltok. Establish more colonies at... Tranome Sar, Cheron, and Devron.
2144 - Imperialization & Militarization
2146 - Tranome Sar
2150 - Cheron
The outer colonies are "imperialized" and the Romulan Imperial Interstellar Navy is established. Tranome Sar and Cheron. Scoutships sent to some of the further worlds not to make contact, but to see what’s there.
And they’re well on their way, as Cheron gets rolling, they find... not Vulcans, but Humans. And these Humans seem annoyed that there are some new kids on the block..
And the Humans are starting to poke around the edges of this thing, and the Romulans get nervous. But there’s nothing serious, just snooping.
First Human-Romulan contact believed to be in 2151-52.
The Kursk Incident
Word gets back to the UESN Command that there’s a new alien race out there. Since these guys have apparently been snooping around they decide to handle this "discretely" without publicity, for the moment.
First shots fired. February (22?) 2153. Oops....
IN early 2152 the UE Intelligence starts getting indications of a previously unknown race that’s expanding beyond the "eastern galactic frontier." Stories from small survey ships that are finding manned stations where there shouldn’t be, alien starships appearing out of nowhere. So they send a joint UESN/UESPA mission out to see what’s out there. They’re heading in towards the inner Romulan territories when they’re found by a Romulan patrol. The Romulans are shadowing them at the extreme edge of sensor range, with countermeasures going on full, trying to figure out who these people are. They think that the UE ships can’t see them. But the Kursk picks up the ships. After a day or two of observation, the Kursk shoots off a message torpedo back home. (Or maybe they launch a small sensor probe to try to scan the Romulans. Or maybe, there’s an extra Romulan cruiser out there that the UE didn’t notice, and accidentally shot the torpedo almost straight at the Romulans. in fact, that would work best. Say that the Romulan ship is trailing almost directly behind the UE ship, hiding in a subspace distortion that is a "byproduct" of the warp field, causing a sensor blind spot. That would explain why they didn’t see that ship) The torpedo’s not really pointed at the Romulans too precisely, but they panic frayed nerves after two days of staring at these unknown aliens, and they shoot the torpedo down. At this point the UE ships realize there are several more Romulan ships than they thought, and think it’s a trap. They take "defensive" action (maneuvers), which isn’t really offensive, but kind of aggressive defense, trying to scare off the ships. Romulans take that as preparation for attack, and open fire. One of the explorer ships, the UES Cortés (CX-22, Republic Class), manages to escape, but the UES Kursk (CC-35, Amarillo Class), and the UES Bradbury (CS-17, Verne Class), are destroyed.
The Romulans think it’s a prelude to invasion sending out scouts to check the area, building up ships. (Hey, it’s what they’d do...) Plus there’s the fact that these new aliens are just as (if not more) advanced then the Romulans themselves.
Other incidents give cause to worry.
In the tradition of fine government, the UE says there’s no reason to worry. I mean, the UESN has plenty of ships. Earth is at total peace with its neighbors, and even if there are some flare-ups, the UE has some cool new boats coming off the assembly line (Amarillo and Pioneer, due to enter full production around 2154-55).
Romulans survey Galorndon Core, September 2153.
Freighter Nakajima Maru is shadowed, January 2154.
Balboa disappears, October 2154.
A few scout and civilian ships moving into the frontier. SEE APPENDIX.
Close Encounters of Another Kind
More hostile encounters the Romulans don’t like these new interlopers, and start chasing Earth ships away in force, though not all encounters are violent most Earth ships exercise the better part of valor.
Who the heck are these aliens? Very little information on them at all,
Romulans also start actively scouting out the "enemy.”
The Forward Policy
What a fine idea! Let’s keep advancing, set up new outposts to get some ground and see what’s out there. There’s supposed to be some powerful alien force out there, but who believes that?...
Station Salem One (Tarod IX) and Pvarto (Gamma Virginis IV) and Cheron are established as forward outposts.
Romulans take Cheron, UE has Tarod both move towards Tomed. Romulans get there first, in the middle of 2155. Although it takes an official shift in strategy for them Tomed is far off the approach vector from Romulus to Vulcan, but it’s an ideal location for a buffer outpost between Earth and Romulus.
Finally acknowledging that something’s going on (February 2155), the UE sends out a First Contact fleet towards one of the "Romulan" planets starting in May 2155.
Battle of Zeta Reticuli... not sure exactly what happened, but degenerated into a big battle that got most of the UE ships destroyed, and the Romulans are mad as hell. The Romulans commit to a war. (End of October 2155). USS Valiant (Pioneer Class) and USS Baikal (Comm relay ship)