Chiefs from all three Armed Forces services and the Chief of the Defence Staff have wished their personnel a merry Christmas.
The past year has seen more UK-based deployments to help bolster COVID defences, while missions abroad have included the landmark Carrier Strike Group deployment.
Admiral Sir Tony Radakin and the heads of the British Army, Royal Navy and Royal Air Force took the opportunity to thank allies and partners for their support – but gave a special mention to military families, while many servicemen and women plan to spend Christmas away from home.
Watch: The Army chief's message.
Chief of the General Staff General Sir Mark Carleton-Smith thanked the Army for a year of "remarkable performance" throughout 2021.
Gen Carleton-Smith said he is "acutely conscious" of families facing a festive period spent with loved ones abroad and wished everyone safety and happiness during the period.
"I hope you come back refreshed and ready for a new set of challenges," he added.
Watch: First Sea Lord wishes Navy a 'peaceful' Christmas.
In a year of constant maritime activity, including the Carrier Strike Group mission, First Sea Lord Admiral Sir Ben Key delivered a personal message of gratitude.
"Whether in the air, on the sea, or below it, whether ashore helping those in distress or rehearsing our skills in order to ensure peace and security around the world, each and every day the Royal Navy has been hard at work," he said.
Watch: RAF personnel thanked for their work and wished a happy Christmas.
Chief of the Air Staff Air Chief Marshal Sir Mike Wigston has wished the RAF a happy Christmas, adding that everyone in the service can "look back with great pride" at what they have achieved in 2021 and look forward to some "really exciting" things in the coming year.
Adm Radakin, the Chief of the Defence Staff, meanwhile, wished all personnel a happy Christmas and thanked "them and their families for what they do on behalf of the nation".