Doing the Jump-Shoot-Jump dance with your Crisis Suits can sometimes leave you relying on that clump of rocks or ruined building for cover, preventing your XV8s from moving away from it. Effectively chaining them to one spot. Well here's how you bring your terrain with you! Adam at Warhammer Tau coined the phrase 'circling the wagons" for this tactic. It refers to XV8s taking cover behind a Hammerhead upgraded with a Disruption Pod and moving and working together for the Tau'Va. This way XV8s can take their cover with them, be protected from assaults and play the moving game which is what the game is all about. This is just one of those Tau Basics. It won't win you the game but it will keep your XV8s alive.
It's called circling the wagons because when this is done with multiple Tau tanks, you effectively build yourself a skimmer wall of protection - a wagon circle if you will.