solarz
Brigadier
Let's try to find some details, how could 600,000 men communicate to do something in an organized manner?
For one thing, a single pitched battle with more hundreds of thousands of men on each side is a rare thing even in Chinese history. The numbers cited are the troop strengths for a *campaign*.
Look at this list:
You will see that most battles that are documented feature strengths in the tens of thousands.
And indeed, communication and organization problems do arise in poorly commanded humongous armies. There are quite a few instances in Chinese history, the most famous of which is probably the Battle of Fei River, where an army in the hundreds of thousands is defeated by an enemy 1/10 of its size.
Medieval European campaigns were fought over single kingdoms or even fiefdoms. Not since the Roman Empire and not until Napoleon did a general try to take on the entire continent. The entire kingdom of France, for example, is the size of a Chinese province, and is far less densely populated. That means much fewer strongholds and garrisons to hold.
That said, we have pretty recent evidence of large armies maneuvering. Take the Korean War, for example. The initial Chinese push consisted of hundreds of thousands of troops, but they were spread out into numerous spearheads all attacking simultaneously. Though they had radio, communication still relied largely on ancient methods such as bugles. The PVA compensated with iron disicipline and a strict adherence to commands and timetables. I.E. if the general orders 2 armies to sweep through enemies and meet up on a certain date, then those armies *will* meet up on that date, even at the cost of huge casualties.