The Siegebreaker fighter archetype grants an ability called Breaker Momentum, which says:
At 2nd level, when a siegebreaker successfully bull rushes a foe, he can attempt an overrun combat maneuver check against that foe as a free action.
This is confusing to me. If I successfully bull rush someone, they are pushed back. However, over run involves moving through other spaces. How do these maneuvers interact? Part of my confusion stems from over run requiring movement, while bull rush does not.