Disney will be releasing a series of four Star Wars Rebels shorts prior to the premiere of the new animated series. The first short is called "The Machine in the Ghost" and it's now available for you to watch below.
In “The Machine in the Ghost,” a special Star Wars Rebels short, the rebels’ Ghost starship is under attack by a wave of TIE fighters. Hera pilots the craft, while Kanan tries to blast the Imperials from the Ghost’s gunner. While they do evade and shoot down several TIEs, it’s up to astromech droid Chopper to finish the job – even if he’s reluctant to do so.
I've also included a clip from the next short from USAToday, which sees Mandalorian warrior Sabine Wren (Tiya Sircar) tagging some Tie-Fighters.