I was most interested to read the anecdote of Sir Charles Napier in William Safire's column ''Exit Haigspeak'' (On Language, July 11). However, I think the circumstances surrounding his message to London, ''Peccavi,'' were rather different, making it an even better pun.

The fighting in the 1840's was at a time of British expansion in India. Nevertheless, there were those in Britain who doubted the wisdom of too rapid an advance, and in particular, the capture of the province of Sind, which was thought likely to lead to an overextension of lines of communication. Napier was therefore under express orders not to capture the territory. Once he discovered, however, how little resistance there was, he took the province with ease. ''Peccavi'' therefore meant both ''I have Sind,'' and ''I have sinned'' - perhaps a perfect pun. MARK BURNYEAT New York City