I don't believe that any individual's actions (whether they be ordinary people or 'great leaders') influences world events. However, I do believe that the actions of the ordinary person, working in concert with other individuals, can greatly influence world events (but not through meditation - through action).
Individual leaders sometimes seem to 'change the course of history', but a closer analysis of the context within which these individuals are operating always shows that prevailing conditions favoured their exercise of power and 'momentous deeds' and they were always backed by powerful elites/groups.