Hammerwiki:Battlefield

Battlefields are locations in RvR areas where you can take keeps or capture objectives.

A battlefield is likely to be centered around a landmark such as a shrine, a farmhouse, an army outpost or some other strategically important location in a zone's RvR area. Players from each Realm will be able to engage in open world RvR combat in battlefields.

Winning a zone in this so-called open RvR is archieved by leveling your own keep until you have siege weapons and conquering the enemy keep afterwards.

Before 1.4, winning the zones was isntead archieved by gathering victory points, until a specific amount was reached or capturing all objectives for a specific, long time.