Right now I'm trying to build a colonial setting for an RPG, in which a group of farmers accidentally uncovers some ruins of great power buried under a swamp while draining it. Before the swamp is completely drained, I'm also planning some kind of conflict as the indigenes (who are aware of what lies beneath the swamp) attempt to stop the swamp from being drained and the ruins from being revealed.

The problem is that I haven't the faintest clue how people actually drain swamps. Google isn't much help here, either: most of the results deal with the ecological consequences of making swamps disappear.

How did people go about draining swamps three hundred years ago? What kind of technology was necessary? Was it a one-person job, or did it take teams of coordinated laborers? Did they use dams to keep water from coming in, or ditches to keep water from going out?

And when they finally succeeded, what was the result? Simply a lower water level? Very muddy (but still usable) land? Dry land?