Prince Charles drew comparisons between the murder of Catholic MP Sir David Amess and Russia's invasion of Ukraine in a ceremony granting Southend-on-Sea city status.
The honour was bestowed on Southend in memory of Sir David who was murdered last October. He had spent decades campaigning for Southend to be made a city.
Addressing a council meeting on Tuesday, Prince Charles recalled meeting Sir David Amess with his wife, the Duchess of Cornwall, in 2014.
He said: "During that visit we recall our conversation with Sir David Amess.
"I knew him of course as a renowned and respected parliamentarian and effective campaigner on many national and local issues. Among them was his passionate determination to secure city status for Southend.
"Today we mark the culmination of that dedicated campaign."
He added: "How we all wish we could celebrate the occasion without the shadow of the dreadful event that took the life of such a devoted public servant."
Prince Charles' thoughts also turned to events in Ukraine, where he said the Russian invasion had been an act of "brutal aggression".
The killing of Sir David, he said, was "an attack on democracy".
"We are seeing those same values under attack today in Ukraine in the most unconscionable way," the Prince said.
Former MP and fellow Catholic Ann Widdecombe read out a statement at the ceremony on behalf of Sir David's family.
"Despite a traumatic and tragic journey we have arrived at the city of Southend-on-Sea. How thrilled our husband and father would have been to know Her Majesty the Queen has bestowed such a huge honour to the people of Southend -on-Sea in his name. A dream come true," the statement said.
"So on his behalf, we the family wish to say thank you to the amazing people in the community who have achieved so much for Southend - this is your day.
"We are all very proud of David and deeply honoured to accept the freedom of the city on his behalf. The very first freedom of Southend-on-Sea ever bestowed.
"A moment in history and a recognition of his love for Southend-on-Sea and its people.
"We are of course filled with sadness he is no longer with us but his legacy is huge and we are so grateful to have had him in our lives and know he will never be forgotten."
Sir David was MP for Southend West from 1997 until the time of his death. He died after being stabbed multiple times inside Belfairs Methodist Church in Leigh-on-Sea, Essex.
Ali Harbi Ali, 25, has been charged with his murder and will stand trial later this month.
