Queen's thanks for welcoming Harry
The Queen has thanked the Australian military for welcoming Prince Harry and said he will "benefit greatly" from the attachment with the "diggers".
Her gratitude was expressed in a message delivered by Harry on her behalf to Australia's Chief of the Defence Force, Air Chief Marshal Mark Binskin.
Harry, a British Army officer who will be leaving the UK's armed forces in June, started his four-week placement with the Australian Defence Force (ADF) by laying a wreath at the country's Tomb of the Unknown Soldier in Canberra - in honour of the nation's war dead - before reporting for duty.
His attachment will see him go on patrol with Aboriginal soldiers and train with the country's special forces.
The Queen's message said: "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.
"Together, our armed forces share skills, resources and resolve in order to uphold and defend our common values.
"In 2015, when together we commemorate the many sacrifices of our countrymen at Gallipoli a century ago, it is fitting that we can also reflect on the strength and persistence today of those common values and our professional military ties.
"I know that Captain Wales will benefit greatly from spending time with the Australian Diggers and I thank you for welcoming him into your ranks. Elizabeth R."
The ADF has said it wants to provide Harry, who is known as Captain Wales in the Army, with an ''authentic military experience''.
Harry's previous experience serving with Australian troops during his time in Afghanistan, and on a charity trek to the South Pole, has ''stoked his enthusiasm'' to work with the country's forces, a Kensington Palace spokesman said.
The prince, wearing his white and black dress uniform bearing three medals, laid a wreath at the Tomb of the Unknown Soldier and observed a minute's silence, as well as placing a poppy at the Roll of Honour.
He then toured the First World War and Afghanistan Galleries at the Australian War Memorial in the capital Canberra, paying special tribute to Australian soldiers who, like him, have served in the recent Middle East conflict.
Harry described as "incredible" a gift of a box made from wood from the Lone Pine tree's descendant that grows on the memorial's grounds.
On presentation Harry was told how A ustralian soldier Mark Smith sent a pine cone back home from the Turkish trenches after searching for three days for his dead brother.
An estimated 1,000 people gathered in the rain to see the prince, who spent about 20 minutes greeting well-wishers, in what is scheduled to be his only public appearance during his time in Australia.
Harry then reported for duty to the Chief of the Defence Force and met senior army personnel before commencing his military exchange with the Australian army.
During his time in the country the Prince will spend time at army barracks in Sydney, training on helicopter simulators in Perth, where he will train with the Special Air Service, and Darwin where he will work with members of Norforce, the mostly indigenous unit that patrols northern Australia.
He is also looking forward to learning how wounded servicemen and women are supported in Australia, having worked with the Ministry of Defence's Personnel Recovery Unit in the UK, Kensington Palace added.
Harry will join his father the Prince of Wales at the Gallipoli commemorations in Turkey on April 24 and 25.
When he leaves the armed forces in June, the royal will spend part of the summer in Africa - a continent he has a great affection for - carrying out voluntary work with field-based conservation experts to learn how local communities in sub-Saharan Africa are working to protect and conserve natural resources and wildlife.
In the autumn, Harry will volunteer with the Ministry of Defence's Recovery Capability Programme supporting the rehabilitation of wounded, injured or sick service personnel where he has been working previously, while he considers what to do next.
Harry has revealed that a decision on his long-term employment prospects has been left open, saying: ''I am considering the options for the future and I am really excited about the possibilities.''
During his 10-year military career the prince went on two tours of duty to Afghanistan and qualified as an Apache Aircraft Commander.
His decision to leave the Army was a surprise to many as he was seen as a passionate member of the forces, who had always dreamt of being a career soldier even as a young boy.