The Battle of the Wheat Fields was a skirmish that took place on the surface of the Real World between members of the Resistance and Machines.
Prelude[]
After Geoffrey had obtained genetically-modified wheat seeds, he convinced Zion to produce wheat on the surface. They found a location where working power lines still stood, far away from the cities that the Machines had taken over, and began to set up ultraviolet (UV) lights. These UV lights, which drew energy from the power lines, allowed the wheat to grow and were protected from the rain by tents that they had put up. Geoffrey's plan had been a success, growing the wheat on the fields and transfering it back to Zion where it was made into bread for everyone to enjoy.
The operation slowly expanded and the skill of both farmers and bakers improved. While the trips to the surface still proved dangerous and problems did occur, they remained undetected by the Machines for years, mostly due to the fact that they were using a relatively small amount of power compared to what the Machines used. Eventually, however, the Machines found out about the wheat fields and moved in to attack.
The Battle[]
The exact events of what was later called the Battle of the Wheat Fields were initially unknown, but Resistance members eventually found out what had happened to Geoffrey and the farmers by retrieving the footages the Surface Seekers recorded during the attack. They found out through their hacking that the farmers stood and fought the Machines as well as they could, but were ultimately no match against them.
Aftermath[]
Wild wheat adapted to the surface
The Resistance also found out that the Machines did not carry the bodies back to the liquefaction facilities, deeming it too costly, and the bodies were simply left in the wheat fields. The bodies nourished the earth, allowing some of the remaining wheat to thrive, adapt and evolve, waiting to be used by future humanity.
Zion did not attempt to start another farming operation on the surface. Instead, they safeguarded whatever stock of grain they had in order to make bread for the citizens twice a year in a celebration called the Bread Feast. Every time the feast was held, Geoffrey's tale was repeated for all citizens to hear so that all may know the man's sacrifices and celebrate it.