https://archive.org/details/alphabeticallist00dodwrich/page/n8
Info on the book: https://blogs.bl.uk/untoldlives/2012/03/bengal-army-officers-names-nationalities-fatalities-and-a-phantom.html
Also
https://wiki.fibis.org/w/Bengal_Army
https://www.familysearch.org/wiki/en/India_Military_Records