The Battle of Xeron was a battle that took place in 3 ABY.
The Alliance ground troops under the command of a major faced steep opposition from the Galactic Empire, which sent in its heavy armed Imperial warbots. Despite not being as large or intimidating as AT-AT walkers, the warbots were hard to neutralize and a unit was captured in order to outline its schematics and find a weakness that could be exploited in later confrontations.
This warbot unit was carried onboard a Rebel ship of the line which brought it to a rendezvous point where Commander Luke Skywalker and the droids C-3PO and R2-D2 could examine it.
- The Complete Star Wars Encyclopedia, Vol. III
- The Essential Atlas