Battle of Termavir

The Battle of Termavir was a battle fought between the Terran Navy and the Coalition between the 13th of March and 26th of March 2646. With over 1500 capital vessels engaged, it is by far the largest naval battle in history. Despite the numerically inferior Terran forces inflicting heavier losses upon Coalition forces, resulting in a tactical victory, the battle is considered a strategic Coalition victory, as it permanently stopped the Terran advance in the Northern Theatre. 
The Federal Navy, made up of much of battlegroup CHIMAERA: the Fourth and the Seventh Armadas; as well as Task Force Tyrant, totaling at around 600 capital vessels with around as many corvettes faced off Allied forces, made up of: 200 capital ships and twice as many corvettes from the Ur Royal Navy, 350 Surben capital vessels with only a handful of corvettes, and over a thousand Mirdesh corvettes accompanying 550 capital ships. The Federal Navy deployed the heaviest ships of the battle: two Saturn-class fleet carriers and five Sol-class dreadnoughts, which dwarfed even the largest Surben cruisers, only about a third their volume. 
The Allied forces proved unable to beat the Terran Navy due to its larger ships. Allied corvettes were decimated by the heavy caliber weaponry mounted on the Terran dreadnoughts, which were able to consistently achieve first-contact shield passthroughs. On the other hand, the shielding and heavy armour of the largest Terran ships made them largely invulnerable to Allied fire in the context of the battle, only one dreadnought was disabled and another one was heavily damaged during the battle, but both were eventually recovered. However, Terran frigates and corvettes proved vulnerable in such a tactically disadvantaged position. Most the Terran corvette fleet was disabled, and over two thirds of frigates were put out of action. This resulted in the end of the Terran advance in the Northern Threatre, as part of Operation Aurelian. Allied losses were however much heavier, the Ur-Han fleet was wiped, nearly all corvettes were destroyed, and over a third of Surben and half of Mirdesh capital ships were destroyed, captured or disabled.