A raid is an attack on a clan. There are two general types of attacks: raids, and cattle raids.
Cattle Raid[]
A cattle raid is an attempt to steal another clan's wealth, generally in the form of cows. Other herd animals such as sheep can also be captured during cattle raids. Cattle raids rely on not being spotted by the victim's defenders, which is why it is advisable not to send too many attackers. A couple of weaponthanes and a handful of footmen are usually enough. However, you may want to send more in case a battle breaks out.
Cattle raids are common practice among the Orlanthi, who believe that if you cannot hold on to your cows, you didn't deserve to have them in the first place. They are common even between allied clans, harmless and do not sour the relationship between the involved parties.
Sometimes, your cattle raids will be stopped short, and your raiders will return home. This is unpredictable and does nothing other than waste the turn.
If a raid is spotted by outer patrols, it might lead to a battle involving a relatively small number of combatants. Cattle Raid battles do not include Heroic Combat, and can only result in the plunder of livestock. These battles have the usual political consequences, because they inevitably result in Orlanthi deaths.
Raid[]
A raid is another type of attack on a clan, usually an attempt to pillage the victim's tula for goods, food and cows, weaken its population, or seize their land.
For more information about the battle system, read the Battle page.