Conversation so far:
When did Harry leave the Army?
Harry's attachment with the ADF ended on 8 May 2015, and on 19 June 2015 his career with the Army ended.
When was he Seconded to the Australian Defence Force?
On 6 April 2015.

Question: What did he do while on duty?
Self-contained rewrite: What did Prince Harry do while on duty in the Australian Defence Force?