I never said you couldn't have an army of over 2 million. If you want to argue that, talk to Nexus.
China's wall is huge. Period.
Yes, I do have plenty of workers. Barbarians don't tend to like you, and those that resist labor can always be forced.
A bombardment of the mines by catapult and ther such siege weapons begins. Archers supplement the siege machines fire.
Avalonian workers redirect a river so that it passes near to the earthen embankments. Using several constructions of a very rough combination between a water wheel and a conveyor belt, and a few archemedes screws that have been quickly fassioned out of copper, the river's waters are being forced into the ring of earth. these machines are being supplemented by lines of men passing buckets uphill, along with cranes, and other such aparatus.
I'm flooding the mines!!! Bloodless battle, only air bubbles.
You may note that I want to extreme cate not to use anything before the year we're at, 0. I even considered not using the archemedes screw, since it was after 500 BC. If that's a problem with the moderator, the screws can magically mysteriously vanish from existence. Won't halt me for long.