The fourth season of Star Wars: The Clone Wars, also known as Battle Lines, consists of twenty-two episodes. It debuted on September 16, 2011 with "Water War" and concluded on March 16, 2012 with "Revenge".
When Anakin is forced to temporarily turn over command of his clone troopers to a new commander, the Jedi Pong Krell, tensions begin to run high as the clones are assigned with a very deadly mission to take the capital of Umbara.
A peace conference between Separatists and Republic delegates is interrupted by Lux Bonteri, the son of a late Separatist Senator, who involves Ahsoka in his dangerous search to find justice for his mother's death.
The disguised Obi-Wan accompanies Cad Bane and Moralo Eval to Serenno, where they enlist in a brutal competition with other bounty hunters from around the galaxy to determine who will participate in a plot to kidnap the Chancellor.