Conversation so far:
How did the Australian Mining Corp with Edgeworth David start?
Edgeworth David wrote a proposal to Senator George Pearce, the Australian Defence Minister, suggesting that the government raise a military force to undertake mining and tunnelling.
What year did this happen when Edgeworth David wrote a proposal to Senator George Pearce, the Australian Defence Minister, suggesting that the government raise a military force to undertake mining and tunnelling?
In August 1915, Edgeworth David wrote a proposal to Senator George Pearce, the Australian Defence Minister, suggesting that the government raise a military force to undertake mining and tunnelling.
Was this establishment of an Australian Mining Corps a military endeavor?
The Australian Mining Corps was a specialist military mining unit of the Royal Australian Engineers during World War I.

Question: Do you know how old he was when this happened?
Self-contained rewrite: Do you know how old Edgeworth David was when the establishment of the Australian Mining Corps happened?