Not exactly historical swordsmanship, but the three against many so clearly points towards the Three Musketeers that I simply have to share this one. The video shows three Olympic level fencers going up against fifty novices. Neither the masters nor the novices seem to have any training in how to fight as a team, but the masters use the crowd against itself very nicely.
You see the masters separating the group and running around to lure out individuals whom they then quickly dispatch. They are able to take out quite a few this way before they get tired of all the running. You will also notice that all the Olympic level fencers are lefties. Lefties are usually said to do better in sword fighting because they have more chances to train against mundanes and mundanes have against lefties. So, most of the 50 novices are fighting against a type of opponent that they have had little chance to practice for. But, when the novices have been thinned out and the masters are tired, the novices finally have their chance. They start working better together (they are less in each other's way) and are able to take out the masters one by one.
Overall, even though you can say a lot about how unrealistic this experiment is and how this sort of an encounter would have worked quite differently with sharp period swords (that had sharp edges and not only the points), the video is still fun to watch and shows how a master can work a group of novices against each other.