Divide and Conquer is the biggest Third Age: Total War submod. The latest release was V5 on July 23rd, 2023. DaC V5- A Kingdom Reuinted features all previous content as well as new features such as the Reunited Kingdom, faction overhauls for Dunland, Enedwaith and the Vale of the Anduin, and overhauled UIs.
More factions, units, settlements, a bigger map.. A must have expansion for original Third Age Total War.
I can't even remember how countless hours I've spent playing this one.. by far the largest submod I've seen as well.