Mentions of 'battlegroup';
sm1-01 brief
[q]
Allied Command has ordered the Aquitaine into the Deneb system. There we will reinforce the 13th Vasudan Battle Group, led by the GVD Psamtik.
[/q]
sm1-06 briefing (NB: informal mention)
[q]
With recent victories on the civil war front, the GTVA Security Council has authorized the deployment of two Deimos-class corvettes into the nebular theatre of operations. The Lysander and the Actium crossed the subspace portal in Gamma Draconis at 2335 hours and joined up with the Aquitaine's battle group.[/q]
sm1-07
[q]This is Lieutenant Samsa. The allied attack against the SD Ravana has deteriorated. We've lost the GTD Delacroix, and the surviving warships in the battle group are damaged. Petrarch is scrambling the 107th to assist. Command will also sortie the GVC Somtus and the GTC Yakiba. Once they cross the subspace portal, we will move them into position.[/q]
loop1-2 (NTF)
[q]As you have no doubt already heard, the GVD Psamtik has destroyed the NTD Cyrene, flagship of the Sirius fleet. As bad as things look in Polaris, the situation in Sirius is even worse. Bosch has redeployed our battle group to reinforce NTF positions in that system.[/q]
loop1-3(NTF); note that 'fleet' is used in the next briefing stage
[q]I'm Lieutenant Commander Jack Niven, your new squadron leader. Commander Snipes has been reassigned, so until further notice, you'll get your orders from me. With the 13th and 11th Vasudan battle groups advancing, we have a hard fight ahead of us. If we lose Sirius, our backs will be against the wall. The NTF has fought too hard to surrender now.
MISSION BRIEFING 2
The 4th Fleet, based in Vega, is providing the Vasudans with logistical support. They've established a cargo depot near the Alpha Centauri jump node. Recon reports a perimeter defense of 16 sentry guns, and fighter patrols inspect the depot at regular intervals. The 185th has been called in to sever that supply line. All targets are of Terran construction.[/q]
sm2-01
[q]News from the Front
At 2150, the Colossus entered the Polaris system and neutralized the NTD Andronicus and the NTC Camisard, securing the jump node from Epsilon Pegasi. Meanwhile, the 13th Vasudan Battle Group has destroyed the NTD Cyrene and gained foothold in Sirius. Intelligence reports that Admiral Bosch and his elite guard have withdrawn to the rebel enclave of Regulus.
Command anticipates a total allied victory in less than 30 days.[/q]
sm2-04
[q]Bosch's Gambit
We have received news of an alarming development on the civil war front. Massing his forces in the Regulus system, Admiral Bosch outmaneuvered the Colossus and its battle group. The rebel armada is now en route for the Gamma Draconis system, via Polaris, Epsilon Pegasi, and Capella.
Their final destination: the Knossos subspace portal.[/q]
sm2-07
[q]Twilight
This is Admiral Khafre, commanding officer of the GVD Psamtik, 13th Vasudan Battle Group.
The NTF rebellion is over. Polaris, Regulus, and Sirius are now under allied control, and we begin the process of rebuilding these systems after 18 months of bloodshed. NTF officers responsible for the genocide of Vasudan civilians will face a war crimes tribunal in Beta Aquilae. GTVA warships in the nebula are now hunting down the Iceni and the other blockade runners.
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DEBRIEFING 2
A Vasudan never leaves the field of battle without authorization from a superior officer. Your cowardice jeopardized the lives of our brothers and sisters. You are hereby stripped of your wings and all privileges bestowed upon you as an officer of the Galactic Terran-Vasudan Alliance. You will be taken into custody and handed over to the Terran 3rd Battle Group authority, where you will face a court martial. You are a disgrace to your species, Terran.[/q]
(NB: debrief is reused elsewhere)
So...... IMO there's use of 'battle group' to describe a group of ships not equal to a fleet, at least in informal terms. The 'formal' use seems to be limited to specific vasudan groups, though.