As they fought the First Imperium the Terrans copied many Vilani concepts of fleet organization, but they came up with a few inovations of their own.
The Terran Expeditionary Strike Group (ESG) was a concept from 21st Century Earth ocean navies applied to interstellar war.
Each ESG had one CV, 2-4 Missile Boats, 0-3 Scouts and 2-3 attack transport ships carrying a Marine Jump Corps. The fighters on board the CV were piloted by Marines and considered part of the Corps Space/Ground force rather than the ESG proper.
The ESG was not considered a front line space combat force or merely a way to protect the transports (although even a lone dreadnought would think twice before engaging a force with such a large volume of missile fire), but instead were designed to seize planets.
Once the Terran front line fleet flattened the Vilani main force each ESGs would jump to a key enemy held planet, take it and hold it until relieved.
The Missile Boats and Fighters would drive off or destroy the enemy space forces then the Fighters would go down with the jump troops to provide fire support.
ESGs also saw considerable action during peacetime doing everything from showing the flag, disaster relief, suppressing planetary revolts or just moving Marine Jump Corps around.
-HJC