Subsidiary alliance

Subsidiary alliance is a system developed by the East India Company by Lord Wellesley. It solved the problem of ruling a nation which is under the rule of a king. 
Some of the rules of the subsidiary alliance were:
Under this doctrine, Indian rulers under British protection surrendered the control of their foreign affairs to the British. Most disbanded their native armies, instead maintaining British troops within their states to protect them from attack. As British power grew, in most parts of India this became increasingly unlikely. The system also allowed the British to maintain their army at the expense of local rulers.