Kandhar had been annexed by Akbar by a stroke of good luck and it continued to be a part of the Mughal Empire throughout the rest of his reign. On account of its strategic position and commercial importance Kandhar was the bone of contention between Indian and Persia.
It was The Gateway to India and a natural base of operations for an invader coming from Central Asia or Persia. The power controlling Kandhar could also easily capture Kabul and that is the reason why the Mughals attached great importance to the possession of Kandhar. Moreover, Kandhar was the place where merchants from India, Central Asia, Turkey and Persia met.
When Akbar died in 1605 and there was the revolt of Prince Khusrau, Shah Abbas, the Persian ruler, instigated the chiefs of Khorasan to attack Kandhar. The Indian Governor put up a stiff resistance. Jahangir also sent reinforcements. The result was that the attack on Kandhar failed. Shah Abbas expressed his complete ignorance of the whole affair. He not only rebuked the Khorasan nobles but also apologised to Jahangir. The matter rested there for the time being.
In 1611, Shah Abbas sent an Ambassador to Agra with rich presents and letters of flattery for Jahangir. Other missions were also sent of the primary purpose of flattering Jahangir and thereby putting him off his guard. Such missions were sent in 1615, 1616 and 1620. In 1621, Shah Abbas sent a large army for the capture of Kandhar. The siege actually started in 1622. When the news reached India, Jahangir ordered Shah Jahan to proceed to Kandhar.
Shah Jahan had his grievances against the treatment meted out to him by Nur Jahan who was advocating the cause of her Son-in-law. Shah Jahan also suspected that he may not be quickly disposed of on the Kandhar Front under the instructions of Nur Jahan. The result was that instead of proceeding to Kandhar he revolted against the Mughal Government.
The Fort of Kandhar fell after the siege of 45 days. Shah Abbas attempted to justify his capture of Kandhar but Jahangir accused him of treachery and deceit. He also order Prince Parvez to recapture Kandhar but the order was cancelled at the instigation of Asaf Khan. The result was that Kandhar could not be recaptured during the reign of Jahangir.