what did the british stand to gain through the system of subsidiary alliance??
The answer to your question is as follows.
The British gained both territorially and financially through the system of subsidiary alliance. The Indian rulers who entered into subsidiary alliance were not allowed to have their own army. The East India Company maintained subsidiary forces on the behalf of these rulers and sought payment from them for the same through their Residents. Failure to make the payment resulted in a portion of their territory being taken away by the British. Thus, it led to revenues for the Company as well as annexation of large territories.
Hope this resolves your query.