The label of Peon denotes the lowest station amongst those in the Orcish Horde. Inferior in all skills of import, these dogs are relegated to menial tasks such as harvesting lumber and mining gold. Their labor is also required for the construction and maintenance of buildings necessary to support the vast undertakings of the Horde. Downtrodden, the Orc Peons slave thanklessly to please their overseers.
Peons are used to mine gold and harvest lumber, and to build and repair buildings and Transports. You must specifically order your Peon to repair a Transport, as right-clicking will make him board it instead.
Peons move significantly slower when carrying gold or lumber.
While their default reaction to being attacked is to flee, they can be ordered to fight. While weak, they can sometimes bring down enemy units through weight of numbers, and even a lone Peon can destroy an undefended Ballista given time.
Attack Peons are a special type of non-buildable unit that can only be added to a map using third-party map editors (the one that comes with the game cannot do it).
They have the same stats as normal Peons and are visually indistinguishable, but cannot gather resources, or build or repair buildings. They lack an attack button, but their default right-click action is to attack. They will also attack automatically if threatened, just like military units.
Peons under computer control will only fight under two conditions:
If they are attacked by an enemy Peasant or Peon (not an Attack Peasant or Peon).
If the computer player cannot rebuild its Great Hall and you have destroyed all or all but one of their buildings, all its remaining Peons will make a last-ditch attack on your base. However, their AI seems to be bugged, as they will move only a few squares, then stop for a second, then move again, stop etc.