Spending Christmas and the end of year festivities away from loved ones in order to protect fellow Australians has been a new experience for some amid the ongoing pandemic restrictions. For members of the Defence Force and their families, they know it's something that may be asked of them in any year.

This season, nearly 1500 Australian service personnel are deployed overseas in mission critical roles in Africa, the Middle East and Afghanistan, and the Pacific. A further 1500 are currently spread across the country as part of Operation COVID-19 Assist, continuing the support that more than 10,000 personnel have contributed to over the course of the pandemic.

Disaster relief and humanitarian assistance has not stopped, with the crew of HMAS Adelaide deploying on Christmas Eve to assist the Fijian government's relief efforts following Tropical Cyclone Yasa.

As communities were devastated by bushfires early in 2020, more than 9000 members of the Defence forces, like many other Australians, cut short their holidays to come to the aid of those in urgent need.

Prime Minister Scott Morrison's Christmas message to the the ADF this year made special note of the impact of their contributions during the bushfires.

"During our Black Summer of fires, we called on you to help keep Australians safe," Mr Morrison said. "Our Army, Navy, Air Force were all deployed flying through orange skies to reach fire-affected communities ... for those who have been through harrowing days and sleepless nights, the arrival of our ADF was the sign that everything was going to be OK.

"The respect that Australians feel for our defence force, men and women, and our veterans is earned. You've earned it through your service that cannot be taken away from you and never should be."

In end-of-year remarks to Defence community, Defence chief Angus Campbell and departmental secretary Greg Moriarty spoke of the pride they felt in those contributions and the privilege to see how their people had risen to the challenges faced by the nation, saving countless lives.

"Our country has asked much of you in 2020," Mr Moriarty said. "Some of you have been separated from your families, endured long quarantine periods and faced extended or uncertain postings.

"We know you have given much this year, and we thank you for your continued service throughout ... the many letters of thanks we have received from communities, schoolchildren and local organisations attest to the profound impact you have had on the lives of our fellow Australians."

Maintaining high spirits and public support faced another challenge later in 2020 when the Inspector General's inquiry concluded with Justice Paul Brereton finding credible evidence that Defence personnel committed and covered up acts of murder while on operations in Afghanistan between 2005 and 2016.

Army chief Rick Burr used his end-of-year message to remind troops that what the Brereton report describes will never happen again, anywhere or in any time.

"We must always be worthy of our nation's trust, and to maintain trust we must acknowledge our mistakes," the Lieutenant General said. "We will come together, as one Army, and support each other. If you need help, please reach out and ask."

A measure of the pressure put on members of the ADF and the enduring challenges faced by veterans has been the spike in calls to Defence and veterans counseling services.