As proven through the WiH campaign itself and my own little experiment. Pre-Capella era ships don't stand a chance against the UEF. With that said, if we faced the UEF instead of the Shivans in Freespace 2. The GTVA probably would of lost.
Whhhhaaaaaaaat?
Pre-Capella era ships (I'm going to assume that means pre-FS2) would lose because they'd have nothing but blob turrets. But come FS2, the GTVA navy is several orders of magnitude more powerful than it was in FS1, even after incorporating shields into its fighters.
If the UEF was invading in FS2 instead of the Shivans, the UEF would have lost handily. Aside from the fact that the UEF fleet would quickly collapse logistically, their personnel have little combat experience, and few of them have experience with any kind of large scale battles/war in general.
There's two ways you can try to fairly compare this:
1) UEF keeps all of its current fighter and ship tech, but no beam jamming (which was thrown together in response to the GTVA invasion, and seemed to only really gain prominence after 18 months of war).
2) UEF get beam jamming, but the rest of its tech is 18 years less advanced (which we'll have to speculate about, or guess).
In (1), GTVA wins thoroughly, but likely takes major casualties in the early stages of the war, mainly in its fighter corps. If the war lasts longer than a short period, then the GTVA will effectively adapt its fighter tactics and take greater advantage of their capital ship superiority. The UEF fighter forces are seriously lacking in terms of mobility--aside from the three Solaris destroyers, none of their ships can carry a decent fighter complement; most operate from local bases in Sol. Ferrying replacements back to the front lines is a risky, lengthy, and complicated process. The UEF will not be able to come up with an effective means of countering beam weapons; it has no AWACS, nor science vessels advanced enough or specialized enough for the task, and converting the few ships up to the task will take significant time. After all, they have to invent the whole process, software, and hardware from scratch. The UEF doesn't have 18 months.
And then the Colossus takes the field, and it's game over.
In (2), assuming the UEF even has any Solaris destroyers at all, you won't be seeing any Kentaroi's or Uriels. The UEF fighters are still a bit superior in many respects, but they can't be fielded in sufficient numbers to turn the tide. Replacements are hard to bring to the front. Logistically, their fighters would cause huge strain on an already logistically problematic situation. UEF ships lack the firepower to truly capitalize on their beam jamming, meaning that ship kills are rare (they usually just retreat). Hecate and Hapshetsut destroyer groups use their massive fighter complements to strike back; UEF fighter forces become outnumbered and whittled down; GTVA replacements and reinforcements are brought up quickly and efficiently--the opposite is the case for the UEF.
TAG missiles are rushed into service, turning the tide. Any ship hit with a TAG missile can be directly and accurately fired upon by all beam cannons (not just slashing ones). Initially tested by the SOC, in which no UEF survivors lived to tell the tale, TAG missiles were first "publicly" used in a huge engagement between the main elements of the UEF and GTVA fleets. Caught completely off-guard, the UEF ships rapidly fall under an onslaught of beam cannons. A general retreat to "their node" is ordered, with a few ships heroically volunteering to screen the retreat, costing them their lives, and buying only moments. However, another GTVA force is waiting for them at the node--they used an AWACS to ensure that none of the UEF ships had warning until they were already jumping in near the node.
Still, the GTVA force blockading the node is clearly not enough to hold against the ravaged, yet still powerful UEF fleet. Then the Colossus shows up, as planned, jumping right into the fight. The UEF personnel present have little time to express their shock, horror, and disbelief as the Colossus opens up with its guns, quickly shredding a trio of ships into ribbons. Many wings of fighters pour from the Colossus' fighter bays.
Another GTVA destroyer jumps in--one of the ones from the first part of the battle, along with several smaller ships supporting it, and some of its fighters. Quickly getting overwhelmed and overrun, some UEF ships jump to random points in the system. As hope is lost, UEF captains quickly begin surrendering. The UEF vessels that fled to other parts of the system are hunted down, ordered to surrender, and if refused, get destroyed by superior firepower and numbers.
