What does the Doctrine of Lapse mean and how did it anger Indian rulers?

The Doctrine of Lapse was a policy used by Lord Dalhousie, the British Governor-General, to expand British territory. Under it, if an Indian ruler died without a natural-born male heir, his kingdom would 'lapse', that is, be annexed by the British, instead of allowing an adopted son to inherit the throne. This ignored the old Indian custom of adopting an heir, which was widely accepted. Using this policy, the British annexed states like Satara, Jhansi and Nagpur. It angered many rulers, who saw it as a cheating device to grab their lands. Rani Lakshmibai of Jhansi, whose adopted son was denied the throne, became a leading figure in the 1857 revolt. So the Doctrine of Lapse is studied as an important political cause of growing resentment against British rule.