QRFs (Quick Reaction Forces) are a fancy name for a "battle". When capturing a base or town/city one will be triggered and a notification will be sent to all players.
A QRF is “won” through a point system, with the number of points per tick per side = number of soldiers + hardware within area x difficulty x time since QRF start. You can track the progress of the QRF at the top of your screen when one is active.
During a QRF, players cannot fast travel to the zone marked as red on the map. You may still respawn inside that zone if your home is there.
Tip: If you know a QRF is coming, set your home to somewhere nearby or it may become very difficult to get back into the fight when you die