Conversation so far:
When did John Owen Brennan's time as a counterterrorism advisor to Obama begin?
On February 27, 2013, the Senate Intelligence Committee postponed a vote on the confirmation of Brennan. On March 5, the Intelligence Committee approved the nomination.
What led to John Owen Brennan's  appointment as counterterrorism advisor for Barack obama?
He advised Obama on foreign policy and intelligence issues during the 2008 election campaign and presidential transition.

Question: Did he have a hand in any historically significant counterterrorism?
Self-contained rewrite: Did John Owen Brennan have a hand in any historically significant counterterrorism?