Gun salutes in all capitals of the United Kingdom as well as aboard some Royal Navy ships on Saturday honoured Prince Philip, the husband of Queen Elizabeth II and the Duke of Edinburgh, who passed away aged 99 at Windsor Castle on Friday.
The 41 rounds fired in London, Cardiff, Belfast and Edinburgh at a rate of one shot per minute from midday local time on Saturday mark the start of an eight-day national mourning period.
"The tradition of Gun Salutes being fired throughout the country to mark significant national events dates back to at least the 18th century, and there are historical records of salutes taking place as early as the 14th century when guns and ammunition began to be adopted more widely, a statement on the royal website read.
"Similar gun salutes were fired to mark the death of Queen Victoria in 1901," it notes.
They also honour the Duke's strong military links, having served with the Royal Navy in World War II.
"His Royal Highness has been a great friend, inspiration and role model for the armed forces and he will be sorely missed, said General Sir Nick Carter, the UK's Chief of the Defence Staff.
People are being asked to watch the gun salutes from a distance as they are broadcast both online and on TV.
In line with the coronavirus pandemic concerns, Buckingham Palace has asked the public to not gather in large numbers at the royal residences and consider making a donation to a charity instead of leaving flowers in memory of the Duke.
An online Book of Condolence has also been launched on the official palace website.
Announcing the Duke's death on Friday, Buckingham Palace said: "It is with deep sorrow that Her Majesty the Queen announces the death of her beloved husband.
"The Royal Family joins with people around the world in mourning his loss."
It is reported that Prince Charles, the heir to the British throne, travelled to Windsor Castle to visit his mother, the Queen, on Friday afternoon.
His sister, Princess Anne, said of her late father that he "treated everyone as an individual, and gave them the respect he felt they were due as individuals".
During the national mourning period, Union flags will be flown at half mast, TV presenters will wear black and Parliament will pass no new laws. As per tradition, the Queen will not carry out any duties either in public or in private, and any new laws requiring Royal Assent will not be sent to her for approval.
Westminster Abbey in London tolled its tenor bell once every 60 seconds for 99 times from 18:00 on Friday, to honour each year of the Duke's life.
His funeral will take place at St. George's Chapel in Windsor Castle, south-east England, but the arrangements have been amended in light of the coronavirus pandemic.
Further details of the royal ceremonial funeral, as opposed to a state funeral in keeping with the royal's wishes, will become clear over the coming days.
Political parties have suspended their campaigning for local elections on May 6 and Parliament is set to honour the Duke with a special House of Commons session on Monday.