Why did Aurangzeb fight with Shuja? 

The fight with Shuja is very surprising. This was the first battle Aurangzeb wanted to avoid and only faught in self defense. Before the succession the only brother Aurangzeb was known to be intimate with was Shuja. After the defeat of Shuja by the forces of Raja Jai Singh and Suleiman Shikoh near Bahadurpur opposite Benaras they pursued him to Mungir. On the news of the victory of Murad and Aurangzeb at Dharmat, Dara panicked and called back Suleiman Shikoh. This let Shuja to escape to Bengal the adobe of his refuge.

• Aurangzeb was busy in pursuing Dara when news reached him of the imminent and hostile intentions of Shuja from Bengal.
• In a departure from the norm Aurangzeb was not anxious to fight Shuja and genuinely intended to overlook his conduct as far as possible.
• But when Shuja audaciously advanced to Benaras he was determined to fight.
• Aurangzeb ordered Prince Muhammad Sultan to march out of Agra.
• Aurangzeb considered it politic to go to the hunting lodge of Soron and wait for the news about Shuja so incase he turned back towards Patna the emperor would recall his troops.
• For the first time Aurangzeb made a genuine effort to settle issue peacefully with Shuja by sending him a letter full of good counsels.
• But when he learnt for certain that gentles ness and mercy would be thrown away on him he set out from Soron to put him down.
• Orders were sent to Prince Sultan not to force an encounter but wait for junction with the Emperor.
• The fate of Shuja would be sealed by the Battle of Khajwa in which he lost to Aurangzeb.
• Prince Sultan was sent off in pursuing him however Shuja managed to escape out of Mughal territories and died at the hands of inhospitable hosts.