The Queen will pay tribute to Britain's armed forces in her Christmas message.
She is head of the armed forces and takes an interest in the efforts of the country's soldiers, sailors and airmen serving overseas and closer to home.
The main operational focus for the UK's servicemen and women has been the continuing battle against the Taliban in Afghanistan, where troops have endured heavy losses during 2009.
Earlier this month the number of deaths suffered by UK forces this year passed the grim milestone of 100.
In her annual address, the Queen will also urge the Commonwealth, especially its youth, to keep on talking about the important things that matter to the institution's 54 member states.
She will say: "It is important to keep discussing issues that concern us all - there can be no more valuable role for our family of nations."
The environment is an issue that has been high on the Commonwealth's agenda and at a gathering of leaders from the institution's member states last month, the Queen urged them to take a "lead" in the international response to the challenge of climate change.
In her message, she will also give a voice to the young people of the Commonwealth, which celebrates its 60th anniversary this year.
Commonwealth youth delegate Serene Koh from Singapore, talking about the institution, will say: "It's a model of friendship that is very important in today's world."
The Queen will deliver her address from Buckingham Palace's White Drawing Room this year.
Her speech is one of the rare occasions when she does not turn to the Government for advice and is able to voice her own views.
It is written by the Queen and usually has a strong religious framework, reflects current issues and often draws on her own experiences.
The message will be transmitted on both television and radio at 3pm on Christmas Day.
The broadcast, produced by ITN, will be available on the Royal Channel on the YouTube website from the same time.
It will also be shown in Commonwealth countries and on the British Forces Broadcasting Service.