Jump gates are also critical to navigation through hyperspace, as each one acts as a beacon in the otherwise featureless void. Ships in hyperspace fly from beacon to beacon until they reach their destination, at which point they either use the jump gate at the destination or their own jump engines to create a vortex back into normal space. Destroying enough jump gates could isolate star systems and cripple interstellar travel.
The beacon network created by jump gates defines the "Rim" of navigable space in the B5 setting. EarthForce has special ships called Explorer ships that are mobile construction facilities capable of building new jump gates, thereby expanding the "Rim". New jump gates must, of course, be built within beacon-receiving range of an existing jump gate.
The "Bonehead" Maneuver
John Sheridan once used a jump gate as an improvised weapon to destroy a Shadow ship. With the vortex in the jump gate still open, he used the hyperdrive on his own ship -- the White Star -- to open another vortex inside the first one. This event created a massive explosion as all of the energy being used to maintain both vortexes was released at once. The actual amount of energy released by the explosion is not known, but it was sufficient to destroy the pursuing Shadow ship, and the White Star was almost unable to escape at maximum acceleration.