The King will refer to "uncertain times" facing the world in his message for Commonwealth Day while celebrating the "source of strength" he believes the body of nations remains to this day.
Writing to mark Commonwealth Day on Monday, the King, as Head of the Commonwealth, will say: "In these uncertain times, where it is all too easy to believe that our differences are problems instead of a source of strength and an opportunity for learning, the Commonwealth's remarkable collection of nations and peoples come together in the spirit of support and, crucially, friendship."
But emphasising his confidence in the relevance of the family of nations, he will add: "The Commonwealth's ability to bring together people from all over the world has stood the test of time and remains as ever-important today."
It comes as the King and his soft diplomatic power have been deployed in recent weeks by the government, in relation to America and Ukraine.
Prime Minister Sir Keir Starmer delivered an extraordinary letter to Donald Trump during his visit to the White House, giving us an unprecedented glimpse into the communications between president and monarch, as Mr Trump held up the letter in front of the gathered press pack.
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King Charles also met with Ukraine's President Zelenskyy when he was in the UK for an emergency summit and following his bruising encounter with Mr Trump.
It has led to questions about how the monarch could be positioned as a non-political and much-respected sounding board at this time of conflict.
The King's full message for Commonwealth Day will be printed in the order of service for the service due to take place on Monday afternoon at Westminster Abbey.
The King and Queen, the Prince and Princess of Wales, the Princess Royal and the Duke and Duchess of Gloucester will join 2,000 members of the congregation.
The theme, 'Together We Thrive', celebrates the enduring spirit of the Commonwealth family, made up of 56 independent member countries.
(c) Sky News 2025: King Charles to celebrate differences as 'a source of strength' in Commonwealth Day message
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