Conversation so far:
When did Prince Harry leave the Army?
Prince Harry left the army in June 2015.
When was Prince Harry seconded to the Australian Defence Force?
Prince Harry spent four weeks throughout April and May 2015 at army barracks in Darwin, Perth and Sydney whilst seconded to the Australian Defence Force (ADF)
What did Prince Harry do while on duty?
While in Perth, he trained with Special Air Service Regiment (SASR), participating in the SASR selection course, including a fitness test and a physical training session with SASR selection candidates.
Did Prince Harry go into any war zones during this time?
Prince Harry was deployed to Afghanistan for 20 weeks  in 2012–13 with the Army Air Corps.
Did Prince Harry train with any Special Forces?
He also joined SASR members in Perth for live-fire shooting exercises with numerous Special Forces weapons at a variety of ranges.
Did Prince Harry do any other training with the Special Forces?
In Sydney, he undertook urban operations training with the 2nd Commando Regiment. Training activities included remotely detonating an Improvised Explosive Device (IED) and rappelling from a building
Did Prince Harry fly with the Air Force?
He spent time flying over Sydney as co-pilot of an Army Black Hawk helicopter

Question: How long did he serve with the Australian Defence Force?
Self-contained rewrite: How long did Prince Harry serve with the Australian Defence Force?