Mangal Pandey confronted British officers at Barrackpore on 29 March 1857, before the larger sepoy uprising broke out at Meerut on 10 May. The wording of “At which cantonment did Mangal Pandey attack British officers on 29 March 1857?” makes Barrackpore decisive because the stem combines a particular date, place and political consequence rather than asking for a loose association. The uprising developed through connected military and civilian centres rather than through a single centrally directed command; Contemporary proclamations, military records and later historical writing must therefore be read with attention to place, date and the role assigned to each participant, a distinction applied here to Barrackpore. By contrast, Meerut, Kanpur and Lucknow refer to alternatives whose dates, theatres or functions differ from the relationship being tested. On that evidence, the supported choice is Barrackpore.