Britain's Prince Harry arrived in Australia on Monday for a four-week placement with the Australian Defence Force (ADF).
The prince, called Captain Wales in his military role, will leave the British Army in June after 10-year service, BBC reported.
He also presented the Queen's letter, in which she wrote: "I am delighted that the long and enduring association between the Australian and British armies will be joined by the military secondment of my grandson, Prince Harry."
"I know that Captain Wales will benefit greatly from spending time with the Australian soldiers and I thank you for welcoming him into your ranks," she wrote.
He laid a wreath at the Tomb of the Unknown Soldier in Canberra before reporting for the duty.
The prince then met Defence Chief Mark Binskin at Duntroon House to report for the duty, ABC reported.
He will spend time with Special Air Service Regiment commandos in Perth and with indigenous soldiers in the Northern Territory. He will also train with the army's Sydney-based 6th Aviation Regiment.
The prince will also undertake an official tour to New Zealand.
