Conversation so far:
What was Robert Stewart, Viscount Castlereagh's early life like?
Robert Stewart, Viscount Castlereagh had recurring health problems throughout his childhood.
What else resulted from Robert Stewart, Viscount Castlereagh's childhood illness?
Robert Stewart, Viscount Castlereagh was sent to The Royal School, Armagh, rather than to England for his secondary education indirectly due to childhood health problems.
How was Robert Stewart, Viscount Castlereagh's time in school?
Robert Stewart, Viscount Castlereagh attended St. John's College, Cambridge, where he applied himself with greater diligence than expected from an aristocrat.
Did Robert Stewart, Viscount Castlereagh have other accomplishments at school besides great diligence?
Robert Stewart, Viscount Castlereagh obtained first class in his last examinations at St. John's College, Cambridge.
What did Robert Stewart, Viscount Castlereagh do after returning to Ireland?
Robert Stewart, Viscount Castlereagh left Cambridge due to an extended illness, and after returning to Ireland did not pursue further formal education.
What was being Chief Secretary for Ireland like for Robert Stewart, Viscount Castlereagh?
Robert Stewart, Viscount Castlereagh became an essential adviser to the inexperienced and unpopular John Pratt, 1st Marquess Camden, who was Stewart's senior by only ten years.

Question: What was he able to achieve during this time?
Self-contained rewrite: What was Robert Stewart, Viscount Castlereagh able to achieve during this time as Chief Secretary for Ireland?