It’s a historical incident which has been the center of many discussions and debates concerning the abilities of both Aurangzeb and Dara Shikoh.
Dara Shikoh, the eldest and most favorite son of Mughal Emperor Shah Jahan died by the hands of his younger brother Aurangzeb in a brutal war of succession in which the other two brothers of Aurangzeb and Dara Shikoh also participated.

(Courtesy: Deccan Herald)
Dara Shikoh was the heir-apparent to the Mughal throne after Shah Jahan because of the favoritism of the Mughal Emperor, but his other three sons –Aurangzeb, Shah Shuja, and Murad were definitely not happy with this because as per the rules of the empire, the one most able in military expertise would get the throne.
This started a battle among the brothers when Shah Jahan was ill and being taken care of by Dara Shikoh in Delhi.
Despite having more power and money, Dara Shikoh failed to make alliances like that of Aurangzeb. Aurangzeb, who was then the general of Deccan, joined his forces with brother Murad.
Aurangzeb, after gaining the control of Agra and imprisoning his own father Shah Jahan, broke off his alliance with Murad and had him executed. He killed Murad because he was promised half of the empire of the brothers gained control of it. Shah Jahan was kept in imprisonment even after Aurangzeb won the battle and the Throne.
The other brother Shah Shuja was first offered the governorship of Bengal but later his army was chased out. He fled to Burma where he was killed.
Aurangzeb now had Dara Shikoh as his sole competitor foe the throne and he captured him by declared that he was not a Muslim anymore. A series of battles took place and Dara Shikoh was betrayed by his own general who handed him over to Aurangzeb.
Dara Shikoh was kept in prison and executed after Aurangzeb’s coronation in Delhi on 30th August, 1658.