The "farmers" in this case are the citizens of Brittania, desperate for aid. They face invasion from the northern barbarians (bandits), and have nothing but a dead currency and their spare worthless supplies to offer as payment. Yet in spite of their poor status, seven warlords are attracted to the cause.
One of them would be named Arturius, him commanding the remnants of the last legion: better trained than all the other warlords in the art of war, and with the finest equipment, yet also with the lowest supplies and the least number of troops; every loss he suffers is irreplaceable, so he knows he is of a dieing kind of soldier. (And, ultimately, yup, he dies.)
There would be three from the Saxons, and three from the Angles. Together, the warlords would forge a loose alliance to stave back the enemy threat until it has been dealt with decisively, working out the particulars later. Each brings their own army, so unlike most variants on the scenario, it's not seven warriors fighting dozens of bandits; it's seven warlords fighting a vastly-numerically-superior force controlled by dozens of enemy chieftains they aim to kill.
The idea was loosely inspired by historical knowledge that Brittania wasn't instantly overwhelmed by barbarians when Rome withdrew its forces, and remembering a tidbit of info which I remember theorizing that the Anglo-Saxons were brought in for actually a similar purpose, not themselves being raiders but being protectors that happened to seize the land they were protecting for themselves.
So I'm planning on doing some fairly decent historical research to see details of that era, in particular, how many kingdoms there ended up. I think there were three Anglo-Saxon kingdoms, which if I'm right about, would be perfect for the number of surviving warlords.
It's highly rough around the edges given my rusty knowledge of that historical era (heck, historians themselves don't know as much about then as they should, and those who're in the know are in the minority because there's so much obsolete information about that time period that most people are similarly in the dark [ha, ha]), but I really like the concept. I certainly think it has potential!